C++ string manipulation

Ok I am lost
I have to write a function (myFunction) to receive a sentence and a word to search in the sentence. If the word is found i must manipulate the sentence so that the word I search for is moved to the front of the sentence.

I have declared it as
void myFunction(char input[],char *search)
{
char * strptr = strstr(input,search);
}

That is all that works so far. I am also not allowed to use the <string> header. only the <cstring>.

Any help would be appreciated.