Strings in C++
Strings in C++
In C++, a string is a sequence of characters used to represent text. Strings are an essential part of programming as they allow us to work with textual data efficiently. Whether you’re dealing with user inputs, file manipulation, or any other text-based operations, understanding how to use strings in C++ is crucial.
Declaration,access and initialization of String in C++
std::string ="value";
ex:
std::string name ="trishaank";//direct declaration and initialization cout<<name;//directly access by string name
Advantages of Using Strings in C++:
Initialising at runtime
#include
using namespace std;
int main()
{
string name;
cout<<"enter a name:"; cin>>name;
cout<<endl;
cout<<"given string is "<<name;
return 0;
}Output:
enter a name:Anurag Sharma given string is Anurag
In the above example, we can see that the string is breaking after white space.to overcome this we use getline() method
getline()
- It is used to accept a string of multiple words i.e it considers whitespace also a character in it
- getline() function takes two parameters.
The first one is std::cin and the second one is the name of our string variable.
#include <iostream>
using namespace std;
int main ()
{
string name;
cout << "\nenter a name:";
getline (cin, name); //reading a string
cout << "\ngiven string is " << name;
return 0;
}
Output:
enter a name:Anurag Sharma given string is Anurag Sharma
Concatenation operator(+)
We can directly join the strings using ‘+’ operator, hence it as an overloaded operator
#include <iostream>
using namespace std;
int main(){
string s1="trish";
string s2="rish";
cout<<s1+s2<<endl;//trishrish
return 0;
}
Output
trishrish
length()
length() function returns the length of the string including whitespace characters.
#include <iostream>
using namespace std;
int main()
{
string name; name = "My name is 3shaank";
cout << name.length() <<endl;//includes whitespaces also
return 0;
}
Output
18
Printing only characters in between
#include <iostream>
using namespace std;
int main()
{
string str1 ("trishank");
cout << str1.substr(1,4) << endl;//charecters from 1 to 4
return 0;
}
Output
rishHere, 4 characters starting from position 1 got printed.
find()
find() function finds the position of the first occurrence of a character#include <iostream>
using namespace std;
int main()
{
string str1 ("3sh");
cout << str1.find('s') << endl;//index of 's'
return 0;
}
Output
1
In this example, find() returned the position of ‘s’ in the string str1.
Find the position of a string in another string.
#include <iostream>
using namespace std;
int main()
{
string str1 ("trishaank kumar");
string str2 ("kumar");
cout <<
str1.find(str2) <<endl; //start index of str2 in str 1
return 0;
}
11
compare()
compare() function compares the value of a string ( str1 ) with another string ( str2 ).- It returns 0 if both the strings are equal.
- It returns a positive value if either str1 > str2 or the first unmatched letter of str1 is greater than that of str2.
- It returns a negative value if either str1 < str2 or the first unmatched letter of str1 is less than that of str2.
clear()
This function clears the data present strings and makes it empty.
#include <iostream>
using namespace std;
int main()
{
string s = "I hate my college";
s.clear();//string became empty
cout << "Value of s is :" << s << endl;
cout<<"size of s"<<s.length();// 0 because empty
return 0;
}
Output
Value of s is : size :0
Example 1
# include <iostream>
using namespace std;
int main()
{
string str1 ("trishaank");
string str2 ("trish");
cout << str1.compare(str2) << endl;
return 0;
}
Output:
4
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