How to Use Stdlib.h
Stdlib.h is a frequently utilized library in the C programming language. The name stdlib stands for Standard Library. Stdlib.h is frequently used in memory pointer allocation which is common in most larger C programs. Another popular use of stdlib.h is its random number generator functions. By using C libraries such as stdlib.h, programmers do not have to reinvent C functions that have already been written by others. In just a few steps, any C programmer can utilize the stdlib.h library.
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Things You'll Need
- C compiler
- Previous experience in writing and compiling simple C programs
Instructions
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Include the stdlib.h library in your C source code by putting "#include <stdlib.h>" with all of the other C libraries you are using at the top. This statement tells the C compiler to include functions from the stdlib.h library in the final executable when called by the C source code.
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In your C program, begin using any functions defined in stdlib.h as needed. No other references or declarations about the library are necessary. For example, a programmer may need to generate a random number. Stdlib.h includes a function called random to generate a random number. The programmer would include "x=random(100);" in the C source code to randomly select a number between 0 and 99 and put it in a variable named x.
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Compile the C program. The command needed to compile depends on the compiler you are using. In many Unix environments, the command "gcc helloworld.c" will use the gcc compiler to compile a C program named helloworld.c. During the compile process, the functions in stdlib.h will be included as needed in the final binary executable program.
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Run the resulting executable generated by the compilation process. The default filename of the final executable depends on the compiler you are using. In many Unix environments with the gcc compiler, the default filename "a.out" is used.
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