For string, find and replace

Question

Finding some text and replacing it with new text within a C string can be a little trickier than expected. I am searching for an algorithm which is fast, and that has a smal

Answer 1

My solution, based on the others, but a bit safer I believe:

#include 
#include 
#include 
#define MAX_SOURCE_SIZE (0x100000)

char * searchReplace(char * string, char *toReplace[], char *replacements[], int numReplacements){
    int i = 0;
    char *locOfToRep;
    char *toRep;
    char *rep;
    int lenToRep,lenStr,lenAfterLocRep;
    static char buffer[MAX_SOURCE_SIZE];
    for(i = 0; i < numReplacements; ++i){
        toRep = toReplace[i];
        rep = replacements[i];
        //if str not in the string, exit.
        if (!(locOfToRep = strstr(string,toRep))){
           exit(EXIT_FAILURE);
        }
        lenToRep = strlen(toRep); 
        lenStr = strlen(string); 
        lenAfterLocRep = strlen(locOfToRep); 

        //Print the string upto the pointer, then the val, and then the rest of the string.
        sprintf(buffer, "%.*s%s%s", lenStr-lenAfterLocRep, string,rep,locOfToRep+lenToRep);

        string = buffer;
    }
    return buffer;
}

int main(){
    char * string = "Hello, world!";
    int numVals;
    char *names[2] = {"Hello", "world"};
    char *vals[2] = {"Goodbye", "you"};
    numVals = 2;
    string = searchReplace(string, names, vals, numVals);
    printf("%s\n",string);
}