C++/Language/While
Содержание
- 1 Make the condition of the while loop always true
- 2 Nesting While Loops
- 3 Update of the value of num was done within the body of the loop
- 4 Use the break keyword to provide the user with the option of quitting the data entry
- 5 While loop Demo
- 6 While loop: outputs the numbers between 1 and 10
- 7 While loop: two conditions
- 8 While statement
Make the condition of the while loop always true
<source lang="cpp">
- include <iostream>
using namespace std; int main(void) {
int num; char choice; bool quit = false; while (true) { cout << "Enter a positive number: "; cin >> num; if (num > 0) break; else { cout << "Number must be positive; try again (Y/N): "; cin >> choice; if (choice != "Y") { quit = true; break; } } } if (quit == false) cout << "The number you entered is " << num << " "; else cout << "You did not enter a positive number"; return 0;
}
</source>
Nesting While Loops
<source lang="cpp">
- include <iostream>
using namespace std; int main(void) {
int x = 0; while (x++ < 5) { int y = 0; while (y++ < 5) cout << "X"; cout << "\n"; } return 0;
}
</source>
Update of the value of num was done within the body of the loop
<source lang="cpp">
- include <iostream>
using namespace std; int main(void) {
int num = 0; while (num++ < 10) cout << num << " "; return 0;
}
</source>
Use the break keyword to provide the user with the option of quitting the data entry
<source lang="cpp">
- include <iostream>
using namespace std; int main(void) {
int num; char choice; cout << "Enter a positive number: "; cin >> num; while (num <= 0) { cout << "Number must be positive; try again (Y/N): "; cin >> choice; if (choice == "Y") { cout << "Enter number: "; cin >> num; } else break; } cout << "The number you entered is " << num << " "; return 0;
}
</source>
While loop Demo
<source lang="cpp">
- include <iostream>
using namespace std; int main(void) {
int num; cout << "Enter a positive number: "; cin >> num; while (num <= 0) { cout << "Positive number: "; cin >> num; } cout << "The number you entered is " << num << " "; return 0;
}
</source>
While loop: outputs the numbers between 1 and 10
<source lang="cpp">
- include <iostream>
using namespace std; int main(void) {
int num = 1; while (num <= 10) { cout << num << " "; num++; } return 0;
}
</source>
While loop: two conditions
<source lang="cpp">
- include <iostream>
using namespace std; int main(void) {
int num; char choice; bool quit = false; cout << "Enter a positive number: "; cin >> num; while (num <= 0 && quit == false) { cout << "Number must be positive; try again (Y/N): "; cin >> choice; if (choice != "Y") { cout << "Enter number: "; cin >> num; } else quit = true; } if (quit == false) cout << "The number you entered is " << num << " "; else cout << "You did not enter a positive number"; return 0;
}
</source>
While statement
<source lang="cpp">
- include <iostream>
using namespace std; int main() {
int x, count = 0; float sum = 0.0; cout << "Please enter some integers: " << endl; while( cin >> x ){ sum += x; ++count; } cout << "The average of the numbers: " << sum / count << endl; return 0;
}
</source>