The syntax of this function is comparatively simple than other functions. Strfun is the name of the function. Following is the declaration for strtok() function. String.ToUpper() - ToUpper function converts string to upper case. This string is actually a one-dimensional array of characters which is terminated by a null character '\0'. str − The contents of this string are modified and broken into smaller strings (tokens). delim − This is the C string containing the delimiters. Insert() Insert the string or character in the string at the specified position. All forms are perfectly valid. The strchr() function shall locate the first occurrence of c (converted to a char) in the string pointed to by s.The terminating null byte is considered to be part of the string. Example: string _string1 = "Strings in F#"; string _string2 = _string1.Replace('F','C'); Console.WriteLine(_string2 ); In the c# there are a lot of predefine string functions are available. We know that a string is a sequence of characters enclosed in double quotes.. For example, "Hello World" is a string and it consists of a sequence of English letters in both uppercase and lowercase and the two words are separated by a white space. All the string functions are given below. This string function in C# is used to replaces the character to get another string in which all occurrences of a particular character in this string are replaced with another specified character. Lets see some string function with example. Strings can create using string-literals, which are sequences of characters with double quotation marks; for example, a string of literal “Computer Notes.” The C library offers a wide array of functions for string operations. Strings and embedded null characters. In .NET, a String object can include embedded null characters, which count as a part of the string's length. Note the use of const, because from the function I’m returning a string literal, a string defined in double quotes, which is a constant.. All these handlers are present inside