Control Flow in C++.

Control Flow in C++. If-else, Loops, aur Jump Statements with Examples

Programming ka asli maza tab aata hai jab aap program ka flow control kar paao — matlab kis line ke baad kya chalega, kab chalega, aur kab rukega. Is blog mein hum C++ ke Control Flow statements ko samjhenge.

1. If-Else & Nested If

if-else ka use tab hota hai jab aapko kisi condition ke basis pe decision lena ho.

Simple If-Else Example:

#include<iostream>
using namespace std;
int main(){
int age;
cout << "Enter your Age: ";
cin >> age;

if (age >= 18) {
    cout << "You can vote!";
} else {
    cout << "Sorry, you can't vote.";
}
return 0;
}

Nested If-Else Example:

#include<iostream>
using namespace std;
int main(){
int marks;
cout << "Marks dijiye: ";
cin >> marks;

if (marks >= 90) {
    cout << "Grade: A";
} else if (marks >= 75) {
    cout << "Grade: B";
} else if (marks >= 50) {
    cout << "Grade: C";
} else {
    cout << "Fail ";
}
return 0;
}

 2. Switch Case

Jab aapke paas multiple fixed options ho (jaise menu system), tab switch use hota hai.

Switch Example:

#include<iostream>
using namespace std;
int main(){
int choice;
cout << "1. Tea\n2. Coffee\n3. Juice\nEnter your choice: ";
cin >> choice;

switch(choice) {
    case 1:
        cout << "You selected Tea.";
        break;
    case 2:
        cout << "You selected Coffee.";
        break;
    case 3:
        cout << "You selected Juice.";
        break;
    default:
        cout << "Invalid choice!";
   }
return 0;
}

3. Loops in C++

Loops ka use repeat karne ke liye hota hai — jab tak condition true hai, loop chalta hai.

For Loop:

for (int i = 1; i <= 5; i++) {
  cout << "Hello " << i << endl;
}

While Loop:

int i = 1;
while (i <= 5) {
  cout << "While loop: " << i << endl;
  i++;
}

Do-While Loop:

int i = 1;
do {
  cout << "Do-While loop: " << i << endl;
  i++;
} while (i <= 5);

4. break, continue, goto

break: loop ko turant rok deta hai.

Example:

for (int i = 1; i <= 10; i++) {
    if (i == 5) {
        break;  // loop yahin ruk jayega
    }
    cout << i << " ";
}
// Output: 1 2 3 4

continue: current iteration skip karta hai.

Example:

for (int i = 1; i <= 5; i++) {
  if (i == 3) {
    continue; // 3 skip hoga
  }
  cout << i << " ";
}
// Output: 1 2 4 5

goto: directly jump karta hai kisi label par (rarely used)

Example:

int n;
cout << "Enter a number: ";
cin >> n;

if (n < 0)
    goto negative;
cout << "Number is positive.";
return 0;

negative:
cout << "Negative number entered!";