main.c


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

#define MAXLINE 256

char *reverse(char *input)
{
unsigned short i = 0;
int length = strlen(input)-2;//length of char array minus NULL and newline
char *output = malloc(sizeof(char)*length+2);//dynamically allocate the char array
if (!output){printf("Malloc failed!\n"); exit(1);}

	while (length != -1)//reverse the string
	{
	output[i] = input[length];//last char of input = first char of output
	++i;//increment the output
	--length;//deincrement the input
	}
output[i] = '\0';//null terminate the reversed string
return output;
}

int main(void)
{
char buff;//for holding the char just read
unsigned short maxline = MAXLINE;//length to malloc by default
char *array=malloc(sizeof(char)*maxline);//allocate heap memory
if (!array){printf("Malloc failed!\n"); exit(1);}//exit if out of memory

unsigned short length = 0;//length of read string
while ((buff = getchar()) != EOF)//read char by char from newline into buff until a EOF is inputted
{

if (length == maxline){maxline+=20; array=realloc(array,sizeof(char)*maxline); if (!array){printf("Realloc failed!"); exit(1);}}//realloc the array to allow for more chars if needed

array[length] = buff;//write the char to the array
if (buff == '\n')//if there's a newline, process the string of chars read
	{
	if (length == 0){length=0; goto skip;}//Don't bother to reverse a string containing just a newline
	array[length+1] = '\0';//add a null terminator to the string
	char *reversed = reverse(array);//reverse the string and return a pointer to the reversed string
	printf("Reversed: %s\n", reversed);//print the reversed string
	free(reversed);//free the malloced memory, to stop memory leaking
	length = 0;//reset length back to 0 ready for a new string
	goto skip;
	}

++length;
skip: ;
}
free(array);//free pointer like a good boy
return 0;
}