no output for while loop with nested switch - c

Question

#include <stdio.h>
int main()
{
char cha;
int m=0;
int f=0;
int tot;
while(cha=='m'||cha=='M'||cha=='F'||cha=='f')
{
printf("What is your gender?(m or f):\n");
scanf(" %c",&cha);
switch (cha)
{
case 'm':
case 'M':
printf("\nYou are a male");
++m;
printf("\nPress a to total up");
break;
case 'f':
case 'F':
printf("\nYou are a female");
++f;
printf("\nPress a to total up");
break;
case 'a':
tot=m+f;
printf("\nThe number of male is %d and the number of female is %d",m,f);
printf("\nThe total of male and female is:%d",tot);
break;
}
}
return 0;
}
So i just meddle around with my code trying to put up a program that can sum up the amount of m and f inputted in the program and end up with no output at all.The program just terminated without showing any output.I try to put semicolon at the end of while expression but the while loop end up doesnt even functioning.What's wrong with my code?

Answer 1

you don't give cha a value.
so it doesn't enter the while.
i think this edition is better. and also error handling is so important.
#include <stdio.h>
int main()
{
char cha;
int m=0;
int f=0;
int tot;
bool end = false;
while(end==false)
{
printf("What is your gender?(m or f):\n");
scanf(" %c",&cha);
switch (cha)
{
case 'm':
case 'M':
printf("\nYou are a male");
++m;
printf("\nPress a to total up");
break;
case 'f':
case 'F':
printf("\nYou are a female");
++f;
printf("\nPress a to total up");
break;
case 'a':
tot=m+f;
end = true;
printf("\nThe number of male is %d and the number of female is %d",m,f);
printf("\nThe total of male and female is:%d",tot);
break;
default:
printf("\nEnter valid sex.");
}
}
return 0;

Answer 2

This loop expression:
while(cha=='m'||cha=='M'||cha=='F'||cha=='f')
is evaluated before cha is given a value by the call to scanf(). So basically you get random behavior since cha is not initialized when that line is first reached. There's a very low chance that it holds any of the valid characters, to the loop exits immediately.
Also, please note that scanf() can fail; you should always check its return value.

Answer 3

while condition never gets true
never gets true you should modify this to work according to you although i have modified your code you can have a look of it.
`#include <stdio.h>
int main()
{
char cha;
int m=0;
int f=0;
int tot;
while(cha!='a')
{
printf("What is your gender?(m or f):\n");
scanf(" %c",&cha);
switch (cha)
{
case 'm':
case 'M':
printf("\nYou are a male");
++m;
printf("\nPress a to total up");
break;
case 'f':
case 'F':
printf("\nYou are a female");
++f;
printf("\nPress a to total up");
break;
case 'a':
tot=m+f;
printf("\nThe number of male is %d and the number of female is %d",m,f);
printf("\nThe total of male and female is:%d",tot);
break;
}
}
return 0;
`}

Answer 4

Hi your while loop is never satisfied as cha was never initialized before the while loop. As per your requirement it should be do while loop instead of a while loop. Modify your code like below:-
int main()
{
char cha;
int m=0;
int f=0;
int tot;
do
{
printf("What is your gender?(m or f):\n");
scanf(" %c",&cha);
switch (cha)
{
case 'm':
case 'M':
printf("\nYou are a male");
++m;
printf("\nPress a to total up");
break;
case 'f':
case 'F':
printf("\nYou are a female");
++f;
printf("\nPress a to total up");
break;
case 'a':
tot=m+f;
printf("\nThe number of male is %d and the number of female is %d",m,f);
printf("\nThe total of male and female is:%d",tot);
break;
}
} while(cha=='m'||cha=='M'||cha=='F'||cha=='f');
return 0;
}