Strings
String is a sequence of characters terminated with a null character \0 at the end. There are two types of strings in C++.
- C-Strings
- Strings that are objects of string class
How to declare strings
Declaring strings is similar to one-dimensional character array. Below is the syntax:
char var-name[size];
// or
string str;How to initialize strings
Strings can be initialized in a number of ways:
char str[] = "OneCompiler";
char str[20] = "OneCompiler";
char str[] ={'O','n','e','C','o','m','p','i','l','e','r','\0'};
char str[20] ={'O','n','e','C','o','m','p','i','l','e','r','\0'};
string str = "OneCompiler";How to read strings from console
#include <iostream>
using namespace std;
int main()
{
char str[20];
cin >> str; // to read the string values from stdin
cout << "You have entered: " << str; // to print the sting
return 0;
}Check Result here
Consider if you have given One Compiler as input in the stdin. Surprisingly you get One alone as output. That is because a white space is present between One and Compiler. So how can you read a entire line which also has white spaces in it.
Consider your input string is Hello Everyone.. Happy Learning!!
#include <iostream>
using namespace std;
int main()
{
string str;
getline(cin, str); // to read string from stdin
cout << "String entered is : " << str ;
return 0;
}Check Result here
String Functions
C++ has various in-built string functions which can manipulate null-terminated strings.
| Function name | Description |
|---|---|
| strlen(str) | to return the length of string str |
| strcat(str1, str2) | to concatenate string str2 onto the end of string str1. |
| strcpy(str1, str2) | To copy string str2 into string str1. |
| strcmp(str1, str2) | returns 0 if str1 and str2 are the same and less than 0 if str1 < str2 and a positive number if str1 > str2 |
| strchr(str, c) | Returns a pointer to the first occurrence of character c in string str |
| strstr(str1, str2) | Returns a pointer to the first occurrence of string str2 in string str1 |
Examples
#include <iostream>
using namespace std;
#include <cstring>
int main()
{
char str1[20] = "Happy";
char str2[20] = "learning";
char str3[20];
char str4[20] = "learning";
int length, cmp , cmp1 ;
length = strlen(str1); // to find length of a string
cout << "length of string is : " << length << endl;
strcat( str1, str2); // concatenates str1 and str2
cout << "Concatenation of str1 and str2: " << str1 << endl;
strcpy(str3, str1); // to copy a string into another
cout << "string copy of str1 to str3 : " << str3 << endl;
cmp = strcmp(str2,str4); // to compare two strings
cout << "string compare result : "<< cmp << endl;
cmp1 = strcmp(str1,str4); // to compare two strings
cout << "string compare result : " << cmp1 << endl;
return 0;
}