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C function to replace a sub string with something in a string.
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| /* | |
| * C function to replace a sub string with something in a string. Would suggest to use glib to avoid memory overwritting or use mallocs. | |
| * You can use malloc() to assign memory to return string and get rid of the last argument but make sure to free it later. | |
| * This function replaces multiple instances of the found substring. To replace single instance, see the comment in the function. | |
| * If you want to dig more into it, check this out: http://creativeandcritical.net/str-replace-c | |
| * | |
| * Date: 23/09/2015 | |
| */ | |
| #include <stdio.h> | |
| #include <string.h> | |
| #include <stdlib.h> | |
| #include <glib.h> // Download from- https://developer.gnome.org/glib/ | |
| void replace_str(char *origString, char *stringToReplace, char *replaceWith, char *resultString); | |
| short int find_str(char *string, char start, char stop, char *foundStr); | |
| // GString functions using glib | |
| void g_string_replace(GString *g_origString, char *stringToReplace, char *replaceWith, GString *g_output); | |
| short int g_find_str(char *string, char start, char stop, GString *foundStr); | |
| void main(){ | |
| char result[200]; | |
| char foundStr[100]; | |
| replace_str("we need to (replace this) whole string.", "(replace this)", "print", result); | |
| printf("%s\n", result); | |
| } | |
| void replace_str(char *origString, char *stringToReplace, char *replaceWith, char *resultString){ | |
| char *found; | |
| char *pointer; | |
| int length; | |
| char *origCopy; | |
| char *copyPointer; | |
| origCopy = malloc(strlen(origString) + 1); | |
| origCopy = strcpy(origCopy, origString); | |
| copyPointer = origCopy; | |
| if(replaceWith != NULL){ | |
| pointer = origString; | |
| // replace 'if' with 'while' to use function to replace multiple instance | |
| if(found = (strstr(pointer, stringToReplace))){ | |
| length = found - pointer; | |
| if (length > 0) | |
| { | |
| replaceResultStr = strncpy(replaceResultStr, pointer, length) + length; | |
| } | |
| replaceResultStr = strcpy(replaceResultStr, replaceWith) + strlen(replaceWith); | |
| copyPointer += length + strlen(stringToReplace); | |
| strcpy(replaceResultStr, copyPointer); | |
| } | |
| else | |
| { | |
| strcpy(replaceResultStr, copyPointer); | |
| } | |
| //strcpy(replaceResultStr, pointer); | |
| } | |
| /* | |
| else{ | |
| strcpy(replaceResultStr, origString); | |
| } */ | |
| free(origCopy); | |
| } | |
| /** | |
| * Function to find and retrieve a substring using | |
| * @param string string to search | |
| * @param start the substring start char | |
| * @param stop the substring end char | |
| * @param foundStr pointer pointing to the copy of found substring | |
| * @return 1 if found else 0 | |
| */ | |
| short int find_str(char *string, char start, char stop, char *foundStr) | |
| { | |
| char *startP; | |
| char *stopP; | |
| if((startP = strchr(string, start)) && (stopP = strchr(startP, stop))) | |
| { | |
| strncpy(foundStr, startP, (stopP - startP) + 1); | |
| *(foundStr + ((stopP - startP) + 1)) = '\0'; | |
| return 1; | |
| } | |
| else | |
| return 0; | |
| } | |
| /* | |
| If using the G library, then use this replace function. it's neat. | |
| */ | |
| void g_string_replace(GString *g_origString, char *stringToReplace, char *replaceWith, GString *g_output) | |
| { | |
| char *found; | |
| char *copy; | |
| char * p; | |
| copy = malloc(g_origString->len + 1); | |
| copy = strcpy(copy, g_origString->str); | |
| p = copy; | |
| if (strlen(replaceWith) > 0) | |
| { | |
| if(found = (strstr(copy, stringToReplace))) | |
| { | |
| if((found-copy) > 0){ | |
| g_string_overwrite_len(g_output, 0, copy, found-copy); | |
| g_string_truncate(g_output, found-copy); | |
| p += (found - copy); | |
| } | |
| else{ | |
| g_string_assign(g_output, ""); | |
| //g_string_truncate(g_output, 0); | |
| } | |
| g_string_append(g_output, replaceWith); | |
| g_string_append(g_output, p + strlen(stringToReplace)); | |
| } | |
| else | |
| { | |
| g_string_assign(g_output, g_origString->str); | |
| } | |
| } | |
| else{ | |
| g_string_assign(g_output, g_origString->str); | |
| } | |
| free(copy); | |
| } | |
| /** | |
| * Function to find and retrieve a substring between the given start and stop chars | |
| * @param string string to search | |
| * @param start the substring start char [not included in output] | |
| * @param stop the substring end char [not included in output] | |
| * @param foundStr GString to be returned containing the found string | |
| * @return 1 if found else 0 | |
| */ | |
| short int g_find_str(char *string, char start, char stop, GString *foundStr) | |
| { | |
| char *startP; | |
| char *stopP; | |
| if((startP = strchr(string, start)) && (stopP = strchr(startP, stop))) | |
| { | |
| // +1 and -1 gets rid of the < > brackets | |
| g_string_overwrite_len(foundStr, 0, startP + 1, (stopP - startP - 1)); | |
| return 1; | |
| } | |
| else | |
| return 0; | |
| } |
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