C++ while executive control statement
The C++ ‘while()’ control executive statement is similar to ‘do() while’ statement.Like the ‘do() while’ statement the ‘while()’ statement is use for iterating a code or program until certain condition has been fulfilled.The pictorial representation of ‘while()’ statement is given below.
Link :C++ do() while statement
The syntax of while statement is given below.
while( expression1 ) { //code1 }
Until the expression expression1 is false the code code1 will keep on executing.A code example is given below.
int ii=0; while( ii<5 ) { cout<< ii << endl ; ++ii; }
Output,
0
1
2
3
4
The code example above prints the number lesser than 5,when reaching 5 the expression ‘i<5' returns false so the program is thrown out of the 'while()' loop.
Another program is given below where we will find out the number of ‘m’ or ‘M’ characters in a string/text.
#include <iostream> using namespace std; int main( ) { char st[]= "Many wonderous and marvelous moments!!" ; int i = 0 , count=0 ; while( i<sizeof(st) ) /**the sizeof(st) gives the total number of characters in 'st' string**/ { if (st[i] == 'm' || st[i] == 'M') { ++count; } ++i ; } cout << "The number of \'m\' characters in \"" << st << "\" is " << count ; cin.get( ); return 0; }
Output,
The number of ‘m’ characters in “Many wonderous and marvelous moments!!” is 4
A point to note,if you want to write double quotation(“”) of single quotation(”) in the console screen when using ‘cout’,always use slash(\) before the quotation like in the above code.