CS50x Coding Contest 2016 - Punctuation

punctuation.c

#include <stdio.h>
#include <string.h>
#include <ctype.h>

#include "cs50.h"

int main(void)
{
    string sentence = GetString();
    int period_flag = 0;
    
    //loop through the sentence given
    for (int i = 0; i < strlen(sentence); i++)
    {
        if (period_flag == 1) //marker to see if we have run across a period or not
        {
            printf("%c", toupper(sentence[i])); //if we have then next character must be uppercase
            period_flag = 0; //reset flag for next period
        }
        else if (sentence[i] == ',')
            printf(", ");
            
        else if (sentence[i] == '.')
        {
            period_flag = 1;
            printf(". ");
        }
        else
            printf("%c", sentence[i]);   
    }
}