[Solved] error: result of comparison against a string literal is unspecified for C [duplicate]

Your code has three issues:

1.

if (a == "david")

a decays to a pointer to the first element of array a.

"david" is a string literal.

With the if Statement, you attempt to compare the address of the array a by the address of the string literal "david". String comparison dies not work that way in C.

Use strcmp() – header string.h to compare strings.

strcmp() returns 0 if the strings are equal. To make the if condition turn true you need to use ! negation operator.

2.

There is a misplaced ; between the if condition and if body. Remove it.

3.

The use of cs50.h is deprecated. If you are not required to use it explicitly, leave your hands off from it.

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

int main (void) {
    char a[20];

    printf("ENTER YOUR NAME FOR READING:\n");

    if (!fgets(a, sizeof a, stdin))
    {
         fputs("Failure at input", stderr);
         // further Error routine.
    }

    a[strcspn(a, "\n")] = 0;

    if (!strcmp(a,"david"))
    {
        printf("...");
    }
}