C Programming - Simple way to reverse a string

[Travercraig]

Right so I made this little C program that lets a user input a string and then outputs that input to the console.

 

I was wondering how I could reverse the string so that whatever the user enters is printed out backwards.

 

Would a for or while loop or something suffice? I'm not really sure how i'd do this to be honest. I'm quite new to C programming and just need something simple for now.

 

Here is the code for the program that just outputs the users input to the console.

#include <stdio.h>int main(){    char str[80];		    printf("Enter a string less than 80 characters: \n");	    scanf("%[^\n]", str);	    printf("Your string is: \"%s\"\n", str);	    return 0;}

[vanished]

yes, I would use a for loop starting at the end and stepping back to the start, outputting those characters, or perhaps for more efficiency adding them to another string, and then dumping that to screen all at once

[manikyath]

i'd probably implement a way to count the length of the string (without \n) and then loop trough it backwards makig a new string character per character, then print that.

[Travercraig]

i'd probably implement a way to count the length of the string (without \n) and then loop trough it backwards makig a new string character per character, then print that.

Hmm, I do recall a function called Strleng, I'm assuming that counts the length of the string. I'll have to read up on it.

[vanished]

I generally deal with C++ but I think this might work:

char newstring[80];int i;for (i = 79; i >= 0; i--)if (str[i] != 0)break;for (int j = 0; i >= 0; i--, j++)newstring[j] = str[i];

[prolemur]

#include <string.h>strrev(str);

?

[Yamoto42]

#include <stdio.h>

int main()

{

int i; // iterator

int len; // cached strlen

char str[80];

char tmp; // For swapping

printf("Enter a string less than 80 characters: \n");

// Will read to str[79] OR '\n', whichever comes first

fgets(str, 80, stdin);

// Counts EVERY time you call it...so lets only count

// once, then save the value

len = strlen(str);

// fgets() will include the '\n'...lets get rid of it.

if ( str[len-1] == '\n' ) {

str[len-1] = '\0';

// And update our saved length

len--;

}

printf("Your string is: \"%s\"\n", str);

// Now we reverse it. We start at the ends and

// work our way to the middle.

for ( i = 0; i < len/2; i++ ) {

tmp = str;

str = str[len-i-1];

str[len-i-1] = tmp;

}

return 0;

}

[Nineshadow]

This is a quick string reverse function :

void strrev(char * str){    if (str)    {        char * end = str + strlen(str) - 1;        while (str < end)        {            swap(str,end);            str++;            end--;        }    }}

where swap() is :

void swap(char *x, char *y){    char temp = *y;    *y = *x;    *x = temp;}