The OpenSSL source code can be downloaded from OpenSSL Source Tarballs or any suitable ftp mirror. There are various versions including stable as well as unstable versions. The source code is managed via. In this video, I teach you how to compile and run a C program, using Sublime Text, GCC and the Command Prompt. Download links:-Sublime Text 2: http:// Cygwin B20: https://www.dropbox.com/sh. Options for Debugging Your Program. GCC has various special options that are used for debugging either your program or GCC. However, this manual is not meant to explain anything about the internals of GCC, so you will have to. In this tutorial I'll show how to simply start programming with FreeRTOS on a STM32Nucleo, using a free GCC/Eclipse based toolchain. A cross compiler is a compiler capable of creating executable code for a platform other than the one on which the compiler is running. For example, a compiler that runs on a Windows 7 PC but generates code that runs on Android. GCC and Make - A Tutorial on how to compile, link and build C/C++ applications. GCC (GNU Compiler Collection)A Brief History and Introduction to GCCThe original GNU C Compiler (GCC) is developed by Richard Stallman, the founder of the GNU Project. Richard Stallman founded the GNU project in 1. Unix- like operating system as free software, to promote freedom and cooperation among computer users and programmers. GCC, formerly for . It is now referred to as . The mother site for GCC is http: //gcc. GCC is a key component of . The GNU Toolchain includes: GNU Compiler Collection (GCC): a compiler suit that supports many languages, such as C/C++, Objective- C and Java. GNU Make: an automation tool for compiling and building applications. GNU Binutils: a suit of binary utility tools, including linker and assembler. GNU Debugger (GDB). GNU Autotools: A build system including Autoconf, Autoheader, Automake and Libtool. GNU Bison: a parser generator (similar to lex and yacc). GCC is portable and run in many operating platforms. GCC (and GNU Toolchain) is currently available on all Unixes. They are also ported to Windows by Min. GW and Cygwin. GCC is also a cross- compiler, for producing executables on different platform. The various GCC versions are: In 1. GCC was released. In 1. 99. 2, GCC version 2 was released which supports C++. In 2. 00. 1, GCC version 3 was released incorporating ECGS (Experimental GNU Compiler System), with improve optimization. In 2. 00. 5, GCC version 4 was released. As of July 2. 01. GCC is 4. 7. 4. Installing GCCGCC (GNU Toolchain) is included in all Unixes. For Windows, you could either install Min. GW GCC or Cygwin GCC. It also included MSYS (Minimal System), which is basically a Bourne shell (bash). Cygwin GCCCygwin is a Unix- like environment and command- line interface for Microsoft Windows. Cygwin is huge and includes most of the Unix tools and utilities. It also included the commonly- used Bash shell. Two versions of GCC are installed, identified via gcc- 3. It also provides symlinks gcc. Versions. You could display the version of GCC via - -version option. GCC) 4. 5. 3. $ gcc- 3 - -version. GCC) 3. 4. 4 (cygming special, gdc 0. GCC) 4. 6. 2. > g++ - -version. GCC) 4. 6. 2. More details can be obtained via - v option, for example. Using built- in specs. For example. > gcc - -help. Man Pages. You can read the GCC manual pages (or man pages) via the man utility. Reading man pages under CMD or Bash shell can be difficult. You could generate a text file via. For Cygwin, it is kept under . Hence, you may need to include the current path (./) in the command. In some Unixes, the output file could be . Furthermore, you may need to assign executable file- mode (x) to the executable file . You need to assign executable file mode via command . We use the - o option to specify the output file name. You may separate compile and link in two steps as follows. Wall - g Hello. cpp. Hello. exe Hello. The options are: -c: compile into object file . By default, the object file has the same name as the source file with extension of . No linking with other object file or library. Linking is performed when the input file are object files . GCC uses a separate linker program (called ld. Compile and Link Multiple Source Files. Suppose that your program has two source files: file. You could compile all of them in a single command. However, we usually compile each of the source files separately into object file, and link them together in the later stage. In this case, changes in one file does not require re- compilation of the other files. The resultant assembly file is . For example. > gcc - v hello. Defining Macro (- D)You can use the - Dname option to define a macro, or - Dname=value to define a macro with a value. The value should be enclosed in double quotes if it contains spaces. Headers (. h), Static Libraries (. Shared Library (. Static Library vs. Shared Library. A library is a collection of pre- compiled object files that can be linked into your programs via the linker. Examples are the system functions such as printf() and sqrt(). There are two types of external libraries: static library and shared library. A static library has file extension of . When your program is linked against a static library, the machine code of external functions used in your program is copied into the executable. A static library can be created via the archive program . When your program is linked against a shared library, only a small table is created in the executable. Before the executable starts running, the operating system loads the machine code needed for the external functions - a process known as dynamic linking. Dynamic linking makes executable files smaller and saves disk space, because one copy of a library can be shared between multiple programs. Furthermore, most operating systems allows one copy of a shared library in memory to be used by all running programs, thus, saving memory. The shared library codes can be upgraded without the need to recompile your program. Because of the advantage of dynamic linking, GCC, by default, links to the shared library if it is available. You can list the contents of a library via . The compiler and linker will not find the headers/libraries unless you set the appropriate options, which is not obvious for first- time user. For each of the headers used in your source (via #include directives), the compiler searches the so- called include- paths for these headers. The include- paths are specified via - Idir option (or environment variable CPATH). Since the header's filename is known (e. The linker searches the so- called library- paths for libraries needed to link the program into an executable. The library- path is specified via - Ldir option (uppercase 'L' followed by the directory path) (or environment variable LIBRARY. In addition, you also have to specify the library name. In Unixes, the library libxxx. In Windows, provide the full name such as - lxxx. The linker needs to know both the directories as well as the library names. Hence, two options need to be specified. Default Include- paths, Library- paths and Libraries. Try list the default include- paths in your system used by the . The settings are applicable to the selected project only. GCC Environment Variables. GCC uses the following environment variables: PATH: For searching the executables and run- time shared libraries (. CPATH: For searching the include- paths for headers. It is searched after paths specified in - I< dir> options. It is searched after paths specified in - L< dir> options. Utilities for Examining the Compiled Files. For all the GNU utilities, you can use . For example. > gcc - c hello. COFF executable not stripped - version 3. PE3. 2 executable (console) Intel 8. MS Windows. For example. A 'T' in the second column indicates a function that is defined, while a 'U' indicates a function which is undefined and should be resolved by the linker. For example. > ldd hello. Windows/SYSTEM3. 2/ntdll. Windows/system. 32/kernel. KERNELBASE. dll => /cygdrive/c/Windows/system. KERNELBASE. dll (0x. Windows/system. 32/msvcrt. GNU Make. The . A makefile consists of a set of rules. A rule consists of 3 parts: a target, a list of pre- requisites and a command, as follows: target: pre- req- 1pre- req- 2 .. The command must be preceded by a tab (NOT spaces). When make is asked to evaluate a rule, it begins by finding the files in the prerequisites. If any of the prerequisites has an associated rule, make attempts to update those first. In the above example, the rule . Again, it does not exist, so make looks for a rule to create it. In other words, the command will be run only if the target is out- dated compared with its pre- requisite. For example, if we re- run the make command. Nothing to be done for `all'. You can also specify the target to be made in the make command. For example, the target . You can then run the make without target, which is the same as . Long line can be broken and continued in several lines via a back- slash (\). Syntax of Rules. A general syntax for the rules is: target. The overall rule is often name . If the target is a file, it will be checked against its pre- requisite for out- of- date- ness. Phony target is always out- of- date and its command will be run. The standard phony targets are: all, clean, install. Variables. A variable begins with a $ and is enclosed within parentheses (..) or braces . Single character variables do not need the parentheses. For example, $(CC), $(CC. There include: $@: the target filename. For example. VPATH = src include. You can also use vpath (lowercase) to be more precise about the file type and its search directory. For example. vpath %. Pattern Rules. A pattern rule, which uses pattern matching character '%' as the filename, can be applied to create a target, if there is no explicit rule. For example. $(COMPILE. OUTPUT. You can list all the rule via - -print- data- base option. A Sample Makefile. This sample makefile is extracted from Eclipse's . Make is actually quite complex, and can be considered as a programming language by itself!! REFERENCES & RESOURCESGCC Manual. For example, the - c option says not to run the linker. Then the output consists of object files output by the assembler. Some options control the preprocessor and others the compiler itself. Yet other options control the. If the description for a particular option does not mention a source language, you can use. Many options have multi- letter names; therefore multiple single- letter options may. For the most part, the order you use doesn't matter. Order does matter when you use several options of the same. L more than once, the directories are searched in the order specified. Also, the placement of the - l option is. Most of. these have both positive and negative forms; the negative form of - ffoo would be - fno- foo. This manual documents only one of these two forms. Explanations are in the following sections. GCC is capable of. Note that you must link with the libobjc library to make an Objective- C program work. Note that you must link with the libobjc library to make an Objective- C ++ program work. Note that in . cxx, the last two letters must both be literally x. Likewise. . C refers to a literal capital C. Such files are also called specs. Such files are also called bodies. Any file name with no recognized suffix is treated this way. This. option applies to all following input files until the next - x option. Possible values for language are. Turn off any specification of a language, so that subsequent files are handled according to their file name suffixes (as they are if - x has not been. If you specify. - pass- exit- codes, the gcc program will instead return with numerically highest error produced by any phase that returned an error indication. The. C, C ++ , and Fortran frontends return 4, if an internal compiler error is encountered. Note that some combinations (for example, - x cpp- output - E) instruct gcc. The linking stage simply is not done. The ultimate output is in the form of an object file for each. The output is in the form of an assembler code file for each non- assembler input file. The output is in the form of preprocessed source code, which is sent to the standard. This applies regardless to whatever sort of output is being produced, whether it be an executable file, an object file, an. C code. Also print the version number of the compiler driver program and of. This is useful for shell scripts to capture the driver- generated. This fails to work on some systems where the assembler is. GNU assembler has no trouble. This will allow intermodule analysis ( IMA ) to be performed by the compiler. Currently the only language for. C. If you pass source files for multiple languages to the driver, using this option, the driver will invoke the compiler(s) that. IMA once each, passing each compiler all the source files appropriate for it. For those languages that do not support IMA. If you use this option in conjunction with. If the - v option is also specified then. If the. - Wextra option has also been specified (prior to the - -help option), then command line options which have no documentation associated with them. For some targets extra target- specific information may. Unlike the - -target- help option however, target- specific options of the linker and assembler will not be. This is because those tools do not currently support the extended - -help= syntax. One case where it does work. So for example to display all the target- specific optimization options the following can be used. The - -help= option can be repeated on the command line. Each successive use will display its requested class of options, skipping those that have. It takes a single comma separated list as an argument, which will be used to invoke the wrapper. This will invoke all subprograms of gcc under . The options read are inserted in place of the original @file option. If file does not exist, or. A whitespace character may be included in an option by surrounding the entire option in either single or. Any character (including a backslash) may be included by prefixing the character to be included with a backslash. The file may itself. GCC recognizes files with these names and compiles them as C ++ programs even. C programs (usually with the name gcc). This program is also useful when precompiling a C header file with a . C. ++ compilations. On many systems, g++ is also installed with the name c++. In C ++ mode, it is equivalent to - std=c++9. It also enables the undesirable and rarely used ISO trigraph. For the C compiler, it disables recognition of C ++ style // comments as well as the . Alternate predefined macros such as . For that, - pedantic is required in addition to - ansi. Some header files may notice this macro and refrain from declaring. ISO standard doesn't call for; this is to avoid interfering with any programs that might. This option is currently only supported when compiling C or C ++ . By specifying a base standard, the compiler will accept all programs following that standard and those using GNU extensions. For example, - std=c. GCC that are incompatible with ISO C9. On the other hand, by specifying a GNU dialect of a standard, all features the. The. particular standard is used by - pedantic to identify which features are GNU extensions given that version of the standard. For example. - std=gnu. C ++ style // comments, while - std=gnu. Same as. - ansi for C code. Note that this standard is not yet fully supported; see < http: //gcc. The names c. 9x and iso. This is the default for C code. When ISO C9. 9 is fully implemented in GCC , this will become the default. Same as - ansi for C ++ code. This is the default for C ++ code. This option enables experimental features that are likely to be. C ++ 0x. The working draft is constantly changing, and any feature that is enabled by this flag may be removed from future versions. GCC if it is not part of the C ++ 0x standard. This option enables experimental features that may be removed in future versions of GCC. This option is accepted and ignored by GCC versions 4. In GCC versions 4. GCC in C9. 9 mode. Using this option is roughly equivalent to adding the . This option was first supported in GCC 4. This option is not supported in C8. This. option is silently ignored in any language other than C. In the case of function definitions, a. K& R- style list of arguments followed by their declarations is also provided, inside comments, after the declaration. You can use the. keywords . You may. want to use the - fno- gnu- keywords flag instead, which has the same effect. In C9. 9 mode (- std=c. The resulting code is often both. In addition, when a function is recognized as a built- in function, GCC may use information about. For example, warnings are given with - Wformat for bad calls to . If a function is named that is not built- in in this version of GCC , this option is ignored. There is no corresponding. This implies - fbuiltin. A hosted environment is one in which the entire standard library. Examples are nearly everything except a kernel. This is equivalent to. This implies - fno- builtin. A freestanding environment is one in which the standard. The most obvious example is an OS kernel. This is. equivalent to - fno- hosted. When - fopenmp is specified, the. Open. MP Application Program Interface v. This option implies. The - ansi option (and - std options for strict ISO C conformance) implies. This option allows a user supplied . The user supplied compilation step can then add in an additional preprocessing step after normal preprocessing but before compiling. The default is to. The semantics of this option will change if . They are now only supported with the - E switch. See the GNU CPP manual for details. The value of such an expression is void. This option is not supported. C ++ . This option should not be used for new. This option, and its inverse, let you make such a program work with the opposite default. Likewise, the option. By. default, such a bit- field is signed, because this is consistent: the basic integer types such as . For example, you might compile a file . Version 2 is the version of the C ++ ABI that first appeared in G++ 3. Version 1 is. the version of the C ++ ABI that first appeared in G++ 3. Version 0 will always be the version that conforms most closely to the C ++. ABI specification. Therefore, the ABI obtained using version 0 will change as ABI bugs are fixed. This switch is mainly useful for working around bugs in the access control code. This check is normally unnecessary. C ++ standard specifies that . In all other cases, when . See also new (nothrow). This saves space in the executable at the cost of not. If you compile with this flag and your program mysteriously crashes after . Friend functions. Annotated C ++ Reference Manual, and versions of G++ before 4. However, in. ISO C ++ a friend function which is not declared in an enclosing scope can only be found using argument dependent lookup. This. option causes friends to be injected as they were in earlier releases. This option violates the C ++ standard, but may be useful. NDEBUG . This does not give user code permission to throw exceptions in. If - fno- for- scope is specified, the scope of variables declared in a for- init- statement extends to the end of. G++, and other (traditional) implementations of C ++ . You can use the keyword . The default is to handle inlines differently so that compiles with and without. This will cause linker errors if these. Currently, the only such diagnostic issued by G++ is the one for a name having. Thus, using - fpermissive will allow some nonconforming code to. This option also implies - fno- implicit- templates. If you don't use those parts of the language, you can save some space by using this flag. Note that exception handling. This information is generally only useful to the G++ development team. This assumption. may not be valid if the program uses a cast to convert an arbitrary integer value to the enumeration type. A limit on the template instantiation depth is needed to detect endless recursions. ANSI/ISO C ++ conforming programs must not rely on a maximum depth greater than 1.
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