Page 74 - C-Language

Suppose we start the program like this:

./some_program abba banana mamajam

Then argc is equal to 4, and the command-line arguments:

• argv[0] points to "./some_program" (the program name) if the program name is available from
the host environment. Otherwise an empty string "".
• argv[1] points to "abba",
• argv[2] points to "banana",
• argv[3] points to "mamajam",
• argv[4] contains the value NULL.

See also What should main() return in C and C++ for complete quotes from the standard.

Examples

Printing the command line arguments

After receiving the arguments, you can print them as follows:

int main(int argc, char **argv)
{
for (int i = 1; i < argc; i++)
{
printf("Argument %d: [%s]\n", i, argv[i]);
}
}

Notes

1. The argv parameter can be also defined as char *argv[].
2. argv[0] may contain the program name itself (depending on how the program was executed).
The first "real" command line argument is at argv[1], and this is the reason why the loop
variable i is initialized to 1.
3. In the print statement, you can use *(argv + i) instead of argv[i] - it evaluates to the same
thing, but is more verbose.
4. The square brackets around the argument value help identify the start and end. This can be
invaluable if there are trailing blanks, newlines, carriage returns, or other oddball characters
in the argument. Some variant on this program is a useful tool for debugging shell scripts
where you need to understand what the argument list actually contains (although there are
simple shell alternatives that are almost equivalent).

Print the arguments to a program and convert to integer values

The following code will print the arguments to the program, and the code will attempt to convert
each argument into a number (to a long):

https://riptutorial.com/ 50