Warning: ignoring return value of ‘scanf’, declared with attribute warn_unused_result

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The writer’s of your libc have decided that the return value of scanf should not be ignored in most cases, so they have given it an attribute telling the compiler to give you a warning.

If the return value is truly not needed, then you are fine. However, it is usually best to check it to make sure you actually successfully read what you think you did.

In your case, the code could be written like this to avoid the warning (and some input errors):

#include <stdio.h>

int main() {
    int t;
    if (scanf("%d", &t) == 1) {
        printf("%d", t);
    } else {
        printf("Failed to read integer.\n");
    }
    return 0;
}

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