Question

First time posting here so I’m sorry if I mess up.
I need to search a string and return any strings containing the search data with the search data highlighted.

Example:
If my initial string is: Hi my name is, and my search term is: name, then the output should be: Hi my NAME is

This is a quick code I wrote that works but it only works once. If I try and search again it seg faults.

I was hoping someone could hint me at a better way to write this because this code is disgusting!

void search(char * srcStr, int n){
    int cnt = 0, pnt,i = 0; 
    char tmpText[500];
    char tmpName[500];
    char *ptr, *ptr2, *ptrLast;
    int num;


    while(*(node->text+cnt) != '\0'){ //finds length of string
        cnt++;
    }
    for(pnt = 0; pnt < cnt; pnt++){ //copies node->text into a tmp string
        tmpText[pnt] = *(node->text+pnt);
    }
    tmpText[pnt+1] = '\0';


        //prints up to first occurrence of srcStr
      ptr = strcasestr(tmpText, srcStr); 
        for(num = 0; num < ptr-tmpText; num++){
            printf("%c",tmpText[num]);
        }

      //prints first occurrence of srcStr in capitals
        for(num = 0; num < n; num++){
            printf("%c",toupper(tmpText[ptr-tmpText+num]));
      }

      ptr2 = strcasestr((ptr+n),srcStr);
        for(num = (ptr-tmpText+n); num < (ptr2-tmpText); num++){
            printf("%c",tmpText[num]);
        } 

        while((ptr = strcasestr((ptr+n), srcStr)) != NULL){
            ptr2 = strcasestr((ptr+n),srcStr);
        for(num = (ptr-tmpText+n); num < (ptr2-tmpText); num++){
            printf("%c",tmpText[num]);
        } 
        for(num = 0; num < n; num++){
                printf("%c",toupper(tmpText[ptr-tmpText+num]));
          }
          ptrLast = ptr;
      }
      //prints remaining string after last occurrence
        for(num = (ptrLast-tmpText+n); num < cnt; num++){ 
            printf("%c",tmpText[num]);
        }
}

Answer 1

Only because I’m stupid lazy and there were no pre-requisites for conformance with multi-byte characters (which makes this a helluva lot harder). There are more efficient ways, but barring a platform with strupr() and strlwr() it is hard to get much simpler.

Note: this takes into account the possibility of the search txt being present in the source in mixed case rather than strictly lower case. If the problem domain is restricted to only substitute exact lower-case matches, the source dup can be dropped as well, thereby making this about a half-dozen fewer lines still.

// search for lower case
void substlwr(char* text, const char* str)
{
    // dup strings for lower case  text and search content, 
    //  and upper case replacement text.
    size_t slen = strlen(str);
    char *lbase = strdup(text);
    char *lstr = strdup(str);
    char *ustr = strdup(str);
    char *found = lbase;
    char *p = NULL;

    // convert lowers and uppers
    for (p=lbase; p && *p; *p++ = tolower(*p));
    for (p=lstr; p && *p; *p++ = tolower(*p));
    for (p=ustr; p && *p; *p++ = toupper(*p));

    // replace all lowers with uppers
    while ((found = strstr(found, lstr)))
    {
        memcpy(text + (found-lbase), ustr, slen);
        found += slen;
    };

    free(lbase);
    free(lstr);
    free(ustr);
}

Sample invoke looks like:

int main(int argc, char *argv[])
{
    char text[] = "Hi! My Name is George.";
    substlwr(text, "name");
    printf("%s\n", text);
    return EXIT_SUCCESS;
}

and output looks like this:

Hi! My NAME is George.