string alltrim(string source) Trim spaces at the beginning and end of the string
string toupper(string source) Transfer the contents of the string to uppercase
string tolower(string source) Transfer the contents of the string to lowercase
 + Matchmaking strings (concatenation)
 = Assigning the value to a string variable
+= Assigns the value of a variable by adding the line to its current content
string itoa(int value) Translate integer value in string
string сtoa(char value) Translate an integer value into a string in the form of a symbol
string sprintf(string format, double value) Translate floating point number to a string
int strcontains(string source,string substr) If the source string contains the substr returns 1 (otherwise 0)
cout << arg1 << arg2 << ... Display the information in the message box