C++ provides following two types of string representations are C-style character string and string class type introduced with Standard C++.
The C-Style Character String:
build with C language and continues to be supported within C++. This string is actually a one-dimensional array of characters which is terminated by a character ‘\0’.
The following declaration and initialization create a string “Hello”. It hold the null character at the end of the array, the size of the character array containing the string is one more than the number of characters in the word “Hello” .
char str[6] = {‘H’, ‘e’, ‘l’, ‘l’, ‘o’, ‘\0’};
we can also write as the following :
char str[] = “Hello”;
Example :
#include <iostream>
// www.=learning2night.com
using namespace std;
int main ()
{
char str[6] = {'H', 'e', 'l', 'l', 'o', '\0'};
cout << "The string is : " << str << endl;
return 0;
}
Some functions from c style
- strcpy(s1, s2); //Copies string s2 into string s1.
- strcat(s1, s2); // Concatenates string s2 onto the end of string s1.
- strlen(s1); Returns;// the length of string s1.
- strcmp(s1, s2);//Returns 0 if s1 and s2 are the same; less than 0 if s1
- strchr(s1, ch);//Returns a pointer to the first occurrence of character ch in string s1.
- strstr(s1, s2);// Returns a pointer to the first occurrence of string s2 in string s1.
To use the functions above we have to include
Example :
#include <iostream>
#include <cstring>
// www.learning2night.com
using namespace std;
int main ()
{
char str1[8] = "Hello";
char str2[8] = "World";
char str3[8];
int len ;
// copy str1 into str3
strcpy( str3, str1);
cout << "strcpy( str3, str1) : " << str3 << endl;
// concatenates str1 and str2
strcat( str1, str2);
cout << "strcat( str1, str2): " << str1 << endl;
// total lenghth of str1 after concatenation
len = strlen(str1);
cout << "strlen(str1) : " << len << endl;
return 0;
}
The String Class in C++:
The standard C++ library provides a string class type that supports all the operations mentioned above, additionally much more functionality. We will study this class in C++ Standard Library but for now let us check the following example:
#include <iostream>
#include <string>
// www.learning2night.com
using namespace std;
int main ()
{
string str1 = "Hello";
string str2 = "World";
string str3;
int len ;
// copy str1 into str3
str3 = str1;
cout << "str3 : " << str3 << endl;
// concatenates str1 and str2
str3 = str1 + str2;
cout << "str1 + str2 : " << str3 << endl;
// total lenghth of str3 after concatenation
len = str3.size();
cout << "str3.size() : " << len << endl;
return 0;
}
beside of the function above strig class prived more functionality are :
- lenghth(); // length of string
- at(int n) // return character at index n;
- empty();// test if string is emplty return true
