CODEWITHSUNDEEP
c++c
Md Tawfique Hossain
Md Tawfique Hossain

Reputation: 53

what is the difference between while(n--) and while(n=n-1)?

What is the difference between while(n--) and while(n=n-1)? When I use while(n=n-1) in my code, I can input less than 1 number.

Example: First input 3 than input 3 times a single number (but not happening this in while(n=n-1)). But when I use while(n--), it's normal.

My code is : 

#include <stdio.h>
#include <stdlib.h>

int main()
{
    int n;
    long long inum;
    scanf("%d", &n);
    while(n--)
    {
        scanf("%lld", &inum);
        if(inum == 0 || inum % 2 == 0)
        {
            printf("even\n");
        }

        else
        {
            printf("odd\n");
        }
    }

    return 0;
}

Upvotes: 5

Views: 13386

Answers (2)

user3071284
user3071284

Reputation: 7100

while(n--) uses n in its body, and the decremented value is used for the next iteration.

while(n=n-1) is the same as while(--n), which decrements and uses this new value of n in its body.

Upvotes: 1

pmg
pmg

Reputation: 108978

The value of n-- is the previous value of n

int n = 10;
// value of (n--) is 10
// you can assign that value to another variable and print it
int k = (n--);                     // extra parenthesis for clarity
printf("value of n-- is %d\n", k);

The value of n = n - 1 is 1 less than the previous value of n

int n = 10;
// value of (n = n - 1) is 9
// you can assign that value to another variable and print it
int k = (n = n - 1);                     // extra parenthesis for clarity
printf("value of n = n - 1 is %d\n", k);

Upvotes: 4

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