检查输入的值是否为整数

Question

So there is my code

void otherdata(int* targetValue, int* count){
    char buffer[256];
    while (1) {
        if (fgets(buffer, sizeof(buffer), stdin)) {
            int lsize = atoi(buffer);
            if (isdigit(lsize) != 0) {
                printf("Target value: %d entered\n", lsize);
                *targetValue = lsize;
                return;
            } else {
            printf("Invalid input. Try again.\n");
            }
        }
    }
}

To me it seems it should work, however it doesn't. I think the problem is with the isdigit() but I don't another way how to check if it is num.

Answer 1

void otherdata(int* targetValue, int* count){
    char buffer[256];
    while(1) {
    if (fgets(buffer, sizeof(buffer), stdin)) {
        int lsize = atoi(buffer);
        if (isdigit(*buffer) != 0) {             // <<< Changed this line.
            printf("Target value: %d entered\n", lsize);
            *targetValue = lsize;
            return;
        } else {
        printf("Invalid input. Try again.\n");
        }
    }
}

}