I am trying to allow only yes or no and exit problem if the answer is either number of other letters. How am i supposed to add it?

#include <stdio.h>

int main(void) {

    char answer;
    scanf("%c", &answer);
    if (answer == 'y') {
        printf("You Entered: 'y'\n");
        printf("\n");
        printf("your turn\n");
        printf("\n");
    
    
    }
    else if (answer == 'n') {
        printf("You Entered: 'n'");
        printf("\n");
        printf("other's turn\n");
        printf("\n");
    }
    else (answer != 'y' && answer != 'n'); {
      if (answer == '%d') {
        printf("You Entered:  '%d'\n", answer);
        printf("You did not enter 'y' or 'n', program now exiting... \n");
    
        if (answer <= 'A' || answer <='a') {
          printf("You Entered:  '%c'\n", answer);
        printf("You did not enter 'y' or 'n', program now exiting... \n");  
    
      }
    }
    return 0;
}

CodePudding user response：

You already made an if block, which will check that the condition

answer == 'y'

is met, then after that there is an else if

else if(answer == 'n')

which will execute ONLY if the previous if statement's condition was not satisfied, AND based on the condition that you set, in this case:

answer == 'n'

Now, if you want to throw an error each and every time the user inputs anything different than those two values, there's no simpler solution than this one: making an else statement.

The else statement will execute ONLY if all other previous ifs and else ifs aren't executed.

Your final code could look like this:

#include <stdio.h>

int main(void) {
    char answer;
    scanf("%c", &answer);
    
    if(answer == 'y') {
        printf("You Entered: 'y'\n");
        printf("your turn\n\n");
    }
    else if(answer == 'n') {
        printf("You Entered: 'n'\n");
        printf("other's turn\n\n");
    }
    else {
        printf("You entered neither 'y' nor 'n', program will now exit...\n");
    }
    
    return 0;
}

CodePudding user response：

Your code have two problems:

1. You are missing a parenthesis at the last of your code and other small errors.

2. if (answer == '%d') this comparison is invalid.

   %d is a format specifier, so it cannot store any value.

After correcting your code, it should look like this:

#include <stdio.h>

int main(void) {

    char answer;
    scanf("%c", &answer);

    if (answer == 'y') {
        printf("You Entered: 'y'\n");
        printf("\n");
        printf("your turn\n");
        printf("\n");
    }
    else if (answer == 'n') {
        printf("You Entered: 'n'");
        printf("\n");
        printf("other's turn\n");
        printf("\n");
    }
    else if (answer != 'y' && answer != 'n') {
        printf("You Entered:  '%d'\n", answer);
        printf("You did not enter 'y' or 'n', program now exiting... \n");
    }
    return 0;
}

Hope this helped you out.

CodePudding user response：

A solution to this is to break the check out into a separate function which can read in a character and return true or false depending on whether the character read is one of 'y' or 'n'.

The return of this can then be checked in main and acted on accordingly.

In this case a conditional without else acts as a sentinel that prevents control flow from continuing by returning 1 if get_yes_or_no returns false.

#include <stdio.h>
#include <stdbool.h>

bool get_yes_or_no(char *ch) {
    if (scanf("%c", ch) == 1 && (*ch == 'y' || *ch == 'n')) 
        return true;

    return false;   
}

int main(void) {
    char answer;

    if (!get_yes_or_no(&answer)) {
        printf("You Entered:  '%d'\n", answer);
        printf("You did not enter 'y' or 'n', program now exiting... \n");
        return 1;
    }

    if (answer == 'y') {
        printf("You Entered: 'y'\n");
        printf("\n");
        printf("your turn\n");
        printf("\n");
    }
    else {
        printf("You Entered: 'n'");
        printf("\n");
        printf("other's turn\n");
        printf("\n");
    }

    return 0;
}