atol() vs. strtol() in C: Which one to use?

When it comes to converting strings to numerical values in C programming language, two common functions are atol() and strtol(). However, which one to use depends on the specific needs of the program.

atol() stands for "ASCII to long integer" and is used to convert a string of digits into a long integer. It is a simple function that takes a string argument and returns its numerical equivalent as a long integer. However, it does not provide any error checking for invalid input, and it may overflow if the input string is too long.

strtol(), on the other hand, is a more powerful function that can handle a wider variety of input formats and provides better error checking. It stands for "string to long integer" and takes three arguments: the input string, a pointer to a character pointer that will be set to the first invalid character in the input (if any), and an integer that specifies the base of the input (e.g. 10 for decimal, 16 for hexadecimal).

In general, if the input string is known to be a simple string of digits and no error checking is required, atol() can be used. However, if the input may contain invalid characters or the program requires error checking, strtol() is the better choice.

In conclusion, both atol() and strtol() have their own specific use cases in C programming. The choice between them depends on the specific needs of the program, and it is important to understand their differences and limitations before using them.