strstrofs("haystack", "ac", 0) == 5;
```
+- **strreplace(old, new, string)** searches for certain characters in a string and replaces them with other characters, as in:
+ ```c
+ strreplace("de", "con", "destruction") == "construction";
+ ```
+
The offset defines from which starting position to search, and the return value is `–1` if no match is found. The offset returned is *0*-based, and to search in the whole string, a start offset of *0* would be used.
- **substring(string, startpos, length)** returns part of a string. The offset is *0*-based here, too.