reverse.c

/* Write a function reverse(s) that reverses the characte string s. 
   Use it to write a program that reverses its input a line at a time. */

#include <stdio.h>
#define MAXLINE 1000

int getlines(char line[], int maxline);
void reverse(char s[]);

int main()
{
        char line[MAXLINE]; /*Current Input Line  */

        while(getlines(line, MAXLINE) > 0){
                reverse(line);
                printf("%s", line);
        }
}


int getlines(char line[], int maxline)
{
        int c, i; 
        for (i=0; i<maxline-1 && (c=getchar())!=EOF && c!='\n'; ++i){
                line[i] = c;
        }
        
        line[i] = '\0';
//        printf("%d\n", i);
        return i;
}

// finds length of input after subtracting null character and endline if it exists and storing it in I
//
// finds length of input after subtracting null character and endline if it exists and storing it in I
// 
void reverse(char s[])
{
        int i, j;
        char temp;

        i = 0;

        while(s[i] != '\0'){ /*find the end of string s */
                ++i;
                
        }
        --i;            /* back off from '\0' */
        
        if(s[i] == '\n'){
                --i; // leave new line in place
        }

        j = 0;          //begining of new string s


        //i stores length of input
        //alters elements of array to be reversed
        printf("i: %d, j: %d\n", i, j);

        while(j < i){
                temp = s[j];
                s[j] = s[i];
                s[i] = temp;
//              printf("i: %d j: %d\n", i, j);
                --i;
                ++j;
}

Write a function reverse(s) that reverses the characte string s. Use it to write a program that reverses its input a line at a time.