CODEWITHSUNDEEP
cfor-loopinitialization
user1809300
user1809300

Reputation: 723

for loop will perform only one loop

I need to make a C program to read the number of students(1<=students<=25) in a class and for every student to read his exam score ex 10/20 15/20 etc(1<=score<=20) and print the max and the max score of students and the average score of class.

I made the program but it performs the for loop only once for some reason.

Can you please help me understand why?

here is the code :

#include <stdio.h>

int main(void) {
    int m,i,b,sum,min,max,mo;
    sum=0;
    while (m<1 || m>25) {
            printf("give number of students ");
            scanf("%d",&m);
    }
    for (i=1; i<(m+1); i++) {
            while (b<1 || b>20) {
            printf("give score of  %d student",i);
            scanf("%d",&b);
            }

            if(i==1) {
                    min=b;
                    max=b;
            }
            else {
                    if(b<min) min=b;
                    if(b>max) max=b;
            }
            sum=sum+b;
    }
    mo=sum/m;
    printf("max is  %d and min is  %d and avg is  %d",max,min,mo);
}

Upvotes: 1

Views: 109

Answers (4)

tempidope
tempidope

Reputation: 863

1. You initialize 'm' here, without any prior value

    int m,i,b,sum,min,max,mo;

2. Without a value, you check for this condition. Which means, a garbage value would be used. (May/May not fulfill your condition)

    while (m<1 || m>25) {

3. The crucial scanf for m is inside the previous while. Without which your FOR would run for a basic i=1 and stop.

    for (i=1; i<(m+1); i++) {

You need to understand about Garbage Values in C and vital step of initializing a variable to an initial value before using it.

You may read more on this link: What is a garbage value/How does it occur in C

Upvotes: 1

alinsoar
alinsoar

Reputation: 15793

You forgot to initialize the B variabkle, so it loops m times, never asking you to insert a score!

Upvotes: 1

Mike
Mike

Reputation: 49373

First - initialize your variables:

int m,i,b,sum,min,max,mo; // these are declared and uninitialized

m = 0;  // now it's initialized to 0
i = 0;
...

If you don't initialize them to something, you don't know what they are to start with.

Second - You need to change the value of b:

for (i=1; i<(m+1); i++) {
        while (b<1 || b>20) {  <-- here you're checking for b being valid
        printf("give score of %d student",i);
        scanf("%d",&b);
        }

So the first time in b will be between 1 and 20, if you don't reset it to something invalid you'll never get here again. After you record the value of b:

    sum=sum+b;
    b = 0;   // we're done with b for now, set it to something invalid for the while()
}

Upvotes: 1

Omkant
Omkant

Reputation: 9204

Not initialized the m and using in while condition

It is undefined behaviour using uninitialized local variable in conditon

Want to implement the same

use 

do
{
  printf("give number of students ");
            scanf("%d",&m);
}
while(m<1 || m>25);

for (i=1; i<(m+1); i++) change the condition as i<=m It's the good technique rather < and then adding 1 Inside this loop use the same do while loop

Upvotes: 1

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