The "setjmp.h" header file in C programming provides a way to perform non-local jumps in a program, which can be used for implementing error handling and exception handling mechanisms.

The two functions defined in the "setjmp.h" header file are:

1. "setjmp": Saves the current execution context and returns zero, or a non-zero value if returning from a previous call to "longjmp".

2. "longjmp": Restores the execution context saved by a previous call to "setjmp" and jumps to the specified location in the program.

Here is an example of using the "setjmp.h" header file in a C program:

#include <stdio.h>
#include <setjmp.h>

jmp_buf buf;

void error() {
    printf("An error occurred!\n");
    longjmp(buf, 1);
}

int main() {
    if (setjmp(buf) == 0) {
        printf("Executing first part of code\n");
        error();
    } else {
        printf("Resuming after error\n");
    }

    printf("Exiting program\n");

    return 0;
}

In this example, the "setjmp.h" header file functions are used to implement a simple error handling mechanism. The "error" function is called to signal an error, which calls "longjmp" to jump back to the location saved by "setjmp". The output of the program will be:

Executing first part of code
An error occurred!
Resuming after error
Exiting program

Note that the behavior of "setjmp" and "longjmp" is implementation-dependent and can have performance implications, so they should be used judiciously.