Thread: Need help with loop

Hello, I need help to understand why its printing (14) thank you.

Code:

#include <stdio.h>
#define N 100
int main()
{
    int i,j;
    for(i=0,j=0;i<N;++j,i+=j);
    printf("%d",j);

}

My version of your code:

Code:

#include <stdio.h>
#define N 100

int main(void)
{
    int i, j;

    for(i = 0, j = 0; i < N; ++j, i += j);

    printf("i == %d, j == %d", i, j);
}

Displays the following:

Code:

i == 105, j == 14

Your loop executes 14 times. Each time you increment j once, ("++j"), and add j to i each time through the loop. ("i += j")

Is this what you meant to do?

In the for loop, "++j, i += j", what is i being incremented by???

Is j being incremented first, then i incremented by j, or the opposite?

This is undefined behavior. Different compilers might interpret this differently.

Try this.

for(i=0,j=0;i<N;++j,i+=j);
so,
i+=j means i=i+j
i=0+1=>1 //i=0,j=1(as j is incremented)
i=1+2=>3
i=3+3=>6
i=6+4=>10
i=10+5=>15
i=15+6=>21
i=21+7=>28
i=28+8=>36
i=36+9=>41
i=41+10=>51
i=51+11=>62
i=62+12=>74
i=74+13=>87 //here j=13 ,when it checks next condtion j becomes 14

next i value is 102,it does not satisfies the condition(i<N (i.e)102<100)
so it comes out of the loop,with j=14 in hand
in the next statement
j is printed
so,j=14

i hope you understand.