Calling a function several times

Within one function, how does one go about making several function calls to another function, depending on a user given number?

I tried using a while loop like this:

Code:

---

while(shift > 0){

  rotate_right(ch);

  shift--;
}

---

But that only calls it once, no matter what number u enter

What you need is a recursive function.... a function that calls itself.

No I can't do that, part of the exercise is to make a function called rotate_right and one called rotate_left and yet another one called encode, i've made rotate_right and left so far...

If the number is negative, encode is supposed to call rotate_left, if the number is positive then encode should call rotate_right

It calls them fine, but it only calls them once, whereas, it needs to call them how many times the user specifies.

I think If you declare 'shift' as static, then whatever it holds will stay in memory. But it also means the memory isn't freed when the function ends, so it might not be the best possibility.

[edit]and theres allways globals[/edit]

Quote:

---

Originally Posted by mike_g

I think If you declare 'shift' as static, then whatever it holds will stay in memory. But it also means the memory isn't freed when the function ends, so it might not be the best possibility.

[edit]and theres allways globals[/edit]

---

Good point, i'll try that, thanks!

I don't believe this is a good point. The provided snippet is alright as is but it is not possible to tell from it why rotate_right wouldn't get called shift times. Unless rotate_right goes into infinite recursion / loop or terminates the program (it means, never returns), it should work correctly.

Post some more code. This is probably a problem with the value of 'shift' before the loop is even entered.

As was said, either shift is 1 at the start of the loop or rotate_right() is being stuck somewhere.... although I can think of one more possibility. If shift is global, another function could be messing with it.

Well here is the code, I can only use encode to call rotate_right, I was doing it for any amount of text, then I found I only have to do it for for 1 character that is entered. Changed the code around a bit, now it just ends after it executes the rotate_right function, I tried several ways for it to return control to the encode function, but I'm not entirely sure how to do that.

Code:

---

#include<stdio.h>

int ch;
int shift;

int encode(int ch, int shift);
int rotate_right(int ch);
int rotate_left(int ch);

int main (int argc, char **argv){
 
  int shift;
  int ch;
  printf("Enter shift: ");
  scanf("&#37;d", &shift);
 
  encode(ch,shift);
 
  return 0;
}

int encode(int ch, int shift){
 
  while(shift > 0){
   
  rotate_right(ch);
  shift--;
  }
  printf("%c", ch); 

  /*while(shift < 0){
   
  rotate_left(ch);
    shift++;
  }*/ 
  return 0;
}   

int rotate_right(int ch){ 
 
  ch = getchar();
    if((ch >= 65 && ch <= 89) || (ch >= 97 && ch <= 121)){
      ch = ch + 1;
    }
    else if(ch == 122){
      ch = ch - 25;
    }
    else if(ch == 90){
      ch = ch - 25;
    } 

  return (0);
}

---

Firstly get rid of the global variables. You should only declare variables at the scope where you need them. If you have variables with the same name declared at all possible scopes it just adds a whole lot of confusion.

From the looks of it you have trouble understanding what passing parameters mean and what the return values of functions mean. ch should be input by user in main() (not rotate) and passed to encode. encode has to pass ch on to rotate_function. Both should return the character after shift, and both encode() and main() should use the return value.

By the way: while loops also act as sort of if-s. The first loop would only run if shift is larger than 0, the second loop only if shift is smaller than 0. After any of these loops shift should be 0.