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  1. #include <stdio.h>
  2. #include <string.h>
  3. #include <stdlib.h>
  4.  
  5.  
  6. char *strreplace(char * string, char * sub, char * replace);
  7.  
  8. int main(void){
  9.     char * mystring = "Here is my string.";
  10. 	char * sub = " ";
  11. 	char * replace = "__++";
  12.  
  13. 	char * newString = strreplace(mystring, sub, replace);
  14. 	printf("new string: %s\n", newString);
  15. 	return 0;
  16. }
  17.  
  18. //my replace
  19. char *strreplace(char *string, char *sub, char *replace)
  20. {
  21. 	if(!string || !sub || !replace) return NULL; // we need all inputs
  22.  
  23. 	char *result = (char*)malloc(1); // malloc memory for new string, will be realloc later
  24. 	if(result == NULL){
  25. 		printf("malloc returned null\n");
  26. 		return NULL;
  27. 	}
  28.  
  29. 	char *pos = string; // set pointer of pos to start of string
  30. 	char *pos1; // pointer to search for sub
  31. 	while((pos1 = strstr(pos, sub))) // search for sub and point to start of memory location
  32. 	{ 
  33.         int len = (pos1 - pos); // length = found memory locatino - beginning of string
  34. 		result = realloc(result, len + strlen(replace) + 1); // realloc result for string + replacemenet string + \0
  35.  
  36.         strncat(result, pos, len); // pull up to this location
  37.         strcat(result, replace); //replace the found (strcat is fine because we already allocated the memory)
  38.         pos = (pos1 + strlen(sub)); // update pos to find next occurance of sub in string
  39. 	}
  40.  
  41. 	// if we aren't at the end of the original string, we need to get what's left of original string
  42. 	if(pos != (string + strlen(string)))
  43. 	{
  44. 		result = realloc(result, strlen(result) + strlen(pos) + 1); // realloc for what is left of original string
  45. 		strcat(result, pos); // get the rest of the original string
  46. 	}
  47.  
  48.  
  49. 	return result; // return new string
  50. }
Runtime error #stdin #stdout 0s 3100KB
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Standard input is empty
stdout
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Standard output is empty
https://ideone.com/YIN8zh
language:
C (gcc 8.3)
created:
11 years ago
visibility:
public

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