Write a program to prompt the user to enter a set of strings and the program would sort and display them in ascending alphabetical order. It is accepted to use the functions in the string.h library in the program.

Sure, here's a C program that prompts the user to enter a set of strings, sorts them using the `qsort()` function from the `stdlib.h` library, and then displays them in ascending alphabetical order:

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#define MAX_STRINGS 100
#define MAX_STRING_LENGTH 100

int compare_strings(const void* a, const void* b) {
    return strcmp(*(const char**)a, *(const char**)b);
}

int main() {
    char strings[MAX_STRINGS][MAX_STRING_LENGTH];
    int num_strings = 0;

    printf("Enter a set of strings (up to %d, one per line, press Ctrl+D to stop):\n", MAX_STRINGS);

    // Read in the strings
    while (num_strings < MAX_STRINGS && fgets(strings[num_strings], MAX_STRING_LENGTH, stdin)) {
        // Remove the newline character at the end
        strings[num_strings][strcspn(strings[num_strings], "\n")] = '\0';
        num_strings++;
    }

    // Sort the strings
    qsort(strings, num_strings, sizeof(char[MAX_STRING_LENGTH]), compare_strings);

    // Display the sorted strings
    printf("Sorted strings:\n");
    for (int i = 0; i < num_strings; i++) {
        printf("%s\n", strings[i]);
    }

    return 0;
}

In this program, the `compare_strings()` function is used as the comparison function for `qsort()`, which takes two `const void*` arguments and returns an integer indicating the relative order of the two elements. The `main()` function prompts the user to enter a set of strings, reads them in using `fgets()`, sorts them using `qsort()`, and then displays them using `printf()`.