printf and it's variants are among the most used and useful string functions that I use. If we're counting other functions in string.h I'd definitely add memset and memcpy. More on reddit.com

C does have strings. It doesn't have a "string data type", but it has strings. A string object in C is not a string because the type system says it's a string, it's a string because of the nature of the bytes that make up the object. Specifically, a C string is "a contiguous sequence of characters terminated by and including the first null character". That definition makes no reference to types at all. This might sound a bit pedantic, but it's actually pretty important. Let's say you have an object declared as follows: char str[100]; Does this object identify a string or not? We cannot answer this unless we know the value being stored in the object. The value might be a string, or it might not be. The type system does not tell us. Somebody just asked me "what is a character in C"... but then they deleted the question. I suspect it was going to lead on to "isn't char a data type?" Yes, char is a data type. But in C a character is given the somewhat more abstract definition "member of a set of elements used for the organization, control, or representation of data", as well as the practical definition of a value stored in a single byte. Essentially I see the notion of a character as being a description of a value, not the type of that value. Characters are often stored in char objects, but they can also be stored in other type objects, like unsigned char and int. For the "character as an element of a string" sense, however, one must think of these characters as being in contiguous bytes in memory. One might typically use a char pointer or an array of char to denote such an object, since they allow you to directly address each character in the string individually. A void pointer would not let you do this so easily, for instance, even though it could just as well point to the first character of a string. More on reddit.com

In C a string is an array of characters. The end of a string is signified by the null character ('\0'). Therefore, to find the length of the string, all you need to do is go through each indexed position until you reach the null character. The index of the null character will the length of the string.

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These are some nice snippets. One detail, startsWith can be optimized far better. It does 2 runs through each string, once for the strlen, and once for the comparison. Instead you should just have your own for loop, and compare the strings character by character until prefix reaches '\0'. You don't even need to check the null termination on the other string because if it's shorter it'll compare falsely at that point. More on reddit.com