Reverse a text algoritm

invert-string.c

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

/**
* @desc Algorithm to reverse a string passed by command line as argument.
* 
* Compile: * gcc -o invert-string.c -o invert
* Run: ./invert SAMARA
*
* @author Samuel T. C. Santos
*/
int main(int argc, char **argv){
	
	char* text = argv[1];

	//Get the text length
	int len = strlen(text);
	char tmp, i, j;

	int middle = len / 2;

	//First character
	printf("first  %c \n" , text[0]);

	//Middle character
	printf("middle %c \n" , text[middle]);

	//last character
	printf("last  %c \n" , text[len-1]);

	//Reverse the string
	for(i=0, j=len-1; i < j; i++, j--){
		tmp = text[i];
		text[i] = text[j];
		text[j] = tmp;
	} 

	printf("Reverse:  %s \n", text);

}