将给定基数中的数字转换为小数

Question

• Parameters: number -- the number you are converting a string
• base -- the base you are converting the numebr to
• • Return: The number as a string in base "base"
• • Return Type: char *

This is my code but it is not working;

char *toBase(int number, int base) { 
   char *result=malloc(80); 
   char *ans=malloc(80); 
   int i=0,j,c; 
   while(number != 0) { 
      result[i] = number % base; 
      number = number / base; ++i;
   } 
   for(j=i-1;j>=0;j--) {
      if(result[j]>=10 && result[j]<=24) {
           printf("%c",(result[j]+55)); 
           *ans++=(result[j]+55);
      } else {
           printf("%d",(result[j])); 
           *ans++=(result[j]);
      } 
   } 
   return ans; 
}

Answer 1

The problem is that you modify the ans pointer in the loop, so when you return ans it no longer points to the beginning of the string, instead it points to where you should terminate the string.

Use a temporary variable initialized to be the same as ans and return the one you don't modify.

It should also be noted that you have a memory leak, you allocate memory for result but you never free it anywhere.

Answer 2

Your problem is in the conversion of the numbers into text

Try to add the value of '0' and 'A' resectively, as

  if(result[j]>=10 && result[j]<=24) {
       printf("%c",(result[j]+'A')); 
       *ans++=(result[j]+'A');
  } else {
       printf("%c",(result[j]+'0')); 
       *ans++=(result[j]+'0');
  }

and make sure to null terminate the string before returning it, like

*ans++ = 0;

and also -- the statement

return ans;

will return the end of the string rather than the start -- so you will have to fix that as well, and of cause fix your memory leaks....