strcpy
strcat
isalpha - Find whether the given character is alphabetic or not
islower - Find whether the given character is lowercase or not
isspace - Find whether the given character is whitespace or not
isupper - Find whether the given character is uppercase or not
mblen - Get the length of a multibyte character from the given string
mbstowcs - Converts string pointer in into character array value
mbtowc - Convert pointer into normal character String
srand - sets a starting point for the sequence generated by rand()
strtod - Converts the string into a double and returns the result
strtof - Converts the string into a float and returns the result
strtol - Converts the string into a long double and returns the result
strtoll - Converts the string into a long long and returns the result
strtoul - converts the string into an unsigned long int according to the base of the number
strtoull - Similar to strtoul() except that it returns an unsigned long long int
toLower - Tests character and converts to lowercase if uppercase
toUpper - Tests character and converts to uppercase if lowercase
isalnum - Find whether the given character is alphanumeric or not
sprintf
gets - Reads characters from stdin
puts - Writes the string to the standard output device
getchar - Read a character from stdin
putchar - Print to the stdout
getc - Reads character from stream
strlen - Find length of the String
strcmp
strlwr
strupr - Returns UpperCase of the string
Swappin by using strcpy function