使用 if 语句检测用户是否输入了特定字符或数字

Question

In my getInput function I am scanning input from the user.

If the user enters 'q' or 'Q' I want to print that the user wishes to exit (the program doesn't have to actually 'exit' in technical terms).

If the user enters any other value, I want to return that value and continue running my program.

So, my question is:

How can I test for a certain character value int-to-char conversion similar to how I've attempted it below?

My program exits if the user enters a character and runs if the user enters an integer, but doesn't properly detect that 'q' or 'Q' has been pressed.

This is the code I have so far:

int getInput() {

  int numSets;
  char quitTest1 = 'q';
  char quitTest2 = 'Q';

  //get number of sets from user
  printf("\nEnter desired amount of random number sets (or 'q'/'Q' to quit): ");
  scanf("%d", &numSets);

  if (numSets == (int)quitTest1 || numSets == (int)quitTest2) {
    printf("Exited");
  }

  else {
    return numSets;
  }

}

I'm probably missing some major principle but I can't seem to find much help on Google.

All answers are appreciated.

Answer 1

Note that

scanf("%d", &numSets);

Will not assign any value to numSets if input is a character, numSets will maintain its previous value, which in this case is unknown since the variable is uninitialized, using it ahead will cause undefined behaviour.

Getting the input as a char array an convert to char or int seems the best option.

Live sample here

int getInput() {

    char numSets[100];
    int number = -1;
    char q;
    char quitTest1 = 'q';
    char quitTest2 = 'Q';

    //get number of sets from user
    printf("\nEnter desired amount of random number sets (or 'q'/'Q' to quit): ");
    fgets(numSets, sizeof(numSets), stdin);
    if (sscanf(numSets, "%d", &number)){
        printf("%d", number); //testing
        return number;
    } 

    if (sscanf(numSets, "%c", &q) && (q == quitTest1 || q == quitTest2))
        printf("Exited");
    else{
        puts("Invalid input");

    return number; //will return -1;
}