Problem in name reverser

Code:

---

#include <stdio.h>
#include <string.h>
void reverse_it(char *buffer,int num)
{
    int i;
    for(i=num;buffer[i]>=0;i--);
}
int main(void)
{
    char name[]="KARIM";
    reverse_it(name,strlen(name));
    puts(name);
    getchar();
    return 0;
}

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i dunno what the problem my code be bad.

Your reverse function isn't doing anything. There is no statement that changes the buffer. Plus, the for loop isn't correct. You don't want buffer[i]>=0, but i>=0.

Quote:

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Originally Posted by elwad

Code:

---

#include <stdio.h>
#include <string.h>
void reverse_it(char *buffer,int num)
{
    int i;
    for(i=num;buffer[i]>=0;i--);
}
int main(void)
{
    char name[]="KARIM";
    reverse_it(name,strlen(name));
    puts(name);
    getchar();
    return 0;
}

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i dunno what the problem my code be bad.

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put a condition to reverse the string in the for loop statement instead of putting a semicolon after it.

now it works but after the loop is done it doesnt work does that mean it doesnt change the hole thing ?

Code:

---

#include <stdio.h>
#include <string.h>
void reverse_it(char *buffer,int num)
{
    int i;
    for(i=num;i>=0;i--){
        printf("%c",buffer[i]);
        }
}
int main(void)
{
    char name[]="KARIM";
    reverse_it(name,strlen(name));
    puts(name);
    getchar();
    return 0;
}

---

Quote:

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Originally Posted by elwad

now it works but after the loop is done it doesnt work does that mean it doesnt change the hole thing ?

Code:

---

#include <stdio.h>
#include <string.h>
void reverse_it(char *buffer,int num)
{
    int i;
    for(i=num;i>=0;i--){
        printf("%c",buffer[i]);
        }
}
int main(void)
{
    char name[]="KARIM";
    reverse_it(name,strlen(name));
    puts(name);
    getchar();
    return 0;
}

---

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yes.the actual name hasn't been changed.u're simply printing the name in reverse order in the reverse function.and after it comes to the main function it prints its original name.if u want to store reverse of KARIM in name u've to take another variable in reverse function that changes the order of name.u can also swap the characters in name in reverse function without using another variable.

Quote:

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Originally Posted by BEN10

yes.the actual name hasn't been changed.u're simply printing the name in reverse order in the reverse function.and after it comes to the main function it prints its original name.if u want to store reverse of KARIM in name u've to take another variable in reverse function that changes the order of name.u can also swap the characters in name in reverse function without using another variable.

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how can i reverse it in whish last char comes first and the one after it comes after it and like that .?

Quote:

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Originally Posted by elwad

how can i reverse it in whish last char comes first and the one after it comes after it and like that .?

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as i said just swap the last and first char and 2nd and the 2nd last char uptil the mid char.this way the string will be reversed.

Quote:

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Originally Posted by BEN10

as i said just swap the last and first char and 2nd and the 2nd last char uptil the mid char.this way the string will be reversed.

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okay thanks i will try

i did it but program crashed

Code:

---

#include <stdio.h>
#include <string.h>
void reverse_it(char *buffer,int length)
{
    int i,x;
    char save;
    for(i=0,x=length;;i++,x--){
        buffer[i]=buffer[x];
        }
}
int main(void)
{
    char name[]="NAME";
    reverse_it(name,strlen(name));
    puts(name);
    getchar();
    return 0;
}

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You need a test in the for loop, so it knows when to quit.

i made i<x but i have no idea why is that but it worked also the name reverser doesnt work that well like name will be EMME and when i added x=length-1 it worked but x=length doesnt work can someone explain why ? thanks alot

Code:

---

#include <stdio.h>
#include <string.h>
void reverse_it(char *buffer,int length)
{
    int i,x;
   
    for(i=0,x=length;i<x;i++,x--){
        buffer[i]=buffer[x];
        }
}
int main(void)
{
    char name[]="NAME";
    int i;
    reverse_it(name,strlen(name));
    puts(name);
    getchar();
    return 0;
}

---

Lengths begin with one, but arrays begin at a zero index, not one.

and why does it not work properly ? i mean name is now EMME ??

Here's a hint: How do you swap two variables?

Once you figure that out, your problems will almost be solved.


Quzah.

Quote:

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Originally Posted by quzah

Here's a hint: How do you swap two variables?

Once you figure that out, your problems will almost be solved.


Quzah.

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you swap it using a 3rd variable

but why would i swap it if i ill only switch from buffer[i]=buffer[x] ??

Because without a temporary variable, what you have currently happens. Watch:

Code:

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cow
[c] = [w]
wow
[w] = [w]
wow

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Oops. Since you overwrote the C, you can't move it over to the W.


Quzah.

yah thanks alot man i understand it now and i did it

Code:

---

#include <stdio.h>
#include <string.h>
void reverse_it(char *buffer,int length)
{
    int i,x;
    char saver;
    for(i=0,x=length-1;i<x;i++,x--){
        saver=buffer[i];
        buffer[i]=buffer[x];
        buffer[x]=saver;
        }
}
int main(void)
{
    char name[]="NAME";
    int i;
    reverse_it(name,strlen(name));
    puts(name);
    getchar();
    return 0;
}

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