Incrementing values using variables

Question

This is my code for incrementing either positively or negatively but somehow the code compiles but dosen't work.

#include <cs50.h>
#include <stdio.h>

int main()
{
    int Ini, Con, Incre;

    //ask user for input
    printf("Initialization: \n");
    scanf("%d", &Ini);

    printf("Condition: \n");
    scanf("%d", &Con);

    printf("Increment: \n");
    scanf("%d", &Incre);

    //how to increment variable
    char PN = '\0';
    {
    printf("\nPositive or Negative increment?\n");
    PN = GetChar();
    int count = 0;

    {
        if(PN == 'P' || PN == 'p')
        {
            for(count = Ini; count < Con; count = (count + Incre));
            printf("%d\n", count);
        }

        else if(PN == 'N' || PN == 'n' )
        {
            for(count = Ini; count > Con; count = (count - Incre));
            printf("%d\n", count);
        }
    }
    }
}

And this is what it compiles

/home/ubuntu/workspace/fooling/ $ make counter clang -ggdb3 -O0 -std=c11 -Wall -Werror -Wshadow counter.c -lcs50 -lm -o counter /home/ubuntu/workspace/fooling/ $ ./counter Initialization: 2 Condition: 30 Increment: 5

Positive or Negative increment? Retry: p 32 /home/ubuntu/workspace/fooling/ $

can you tell me where i went wrong?

Answer 1

It looks like you need to review the construction of a for loop. Look at the following:

        for(count = Ini; count < Con; count = (count + Incre));
        printf("%d\n", count);

As written, the for loop will until the condition is no longer met, but will not do anything other than change the value of count. Note the semicolon at the end of the line on the for loop statement. This essentially means for(...;...;...) do nothing;. The printf statement will execute once and only once, since it follows the loop, but is not part of the loop.

If you had wanted to execute the printf statement as part of the loop, then a single line of code to be executed should be between the for loop setup statement and a terminating semicolon, or the for loop setup line should have been followed by a curly brace pair with a block of code inside, like this:

for(...;...;...)
{
    //code block here
}

This is the preferred way to write a for loop.

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