C++ में Nested for Loops

एक nested for loop एक loop को दूसरे के अंदर रखता है, inner loop outer loop की हर iteration के लिए पूरी तरह चलती है, आमतौर पर grids, patterns, और 2D array traversal के लिए इस्तेमाल होता है।

In this page:

Nested for Loop क्या है?
एक Grid Pattern Print करना
एक 2D Array पर Nested Loops
अलग Bounds वाले Nested Loops
Nested Loops की Performance

Syntax

cpp

for (int outer = start; outer < limit; outer++) {
  for (int inner = start; inner < limit; inner++) {
    // inner body
  }
}

Nested for Loop क्या है?

एक nested for loop एक for loop को पूरी तरह दूसरे की body के अंदर रखता है, और inner loop outer loop की हर single iteration के लिए अपनी पूरी range एक बार चलती है।

उदाहरण: What is a Nested for Loop?

cpp

// Include std::cout and std::cin
#include <iostream>

// Program execution starts in main()
int main() {
	// Loop: repeat while the condition holds
	for (int i = 1; i <= 2; i++) {
		// Loop: repeat while the condition holds
		for (int j = 1; j <= 3; j++) {
			// Print to the console with cout
			std::cout << i << "-" << j << " ";
		}
	}
	// Print to the console with cout
	std::cout << std::endl;
	// Return 0 to signal that the program finished successfully
	return 0;
}

एक Grid Pattern Print करना

Nested loops grids या triangles जैसे two-dimensional patterns print करने की standard technique हैं, outer loop आमतौर पर rows control करता है और inner loop हर row के अंदर columns control करता है।

उदाहरण: Printing a Grid Pattern

cpp

// Include std::cout and std::cin
#include <iostream>

// Program execution starts in main()
int main() {
	// Loop: repeat while the condition holds
	for (int row = 1; row <= 3; row++) {
		// Loop: repeat while the condition holds
		for (int col = 1; col <= 3; col++) {
			// Print to the console with cout
			std::cout << "* ";
		}
		// Print to the console with cout
		std::cout << std::endl;
	}
	// Return 0 to signal that the program finished successfully
	return 0;
}

एक 2D Array पर Nested Loops

एक two-dimensional array पर iterate करना लगभग हमेशा nested loops इस्तेमाल करता है, outer loop का index एक row select करता है और inner loop का index उस row के अंदर एक column select करता है।

उदाहरण: Nested Loops over a 2D Array

cpp

// Include std::cout and std::cin
#include <iostream>

// Program execution starts in main()
int main() {
	int grid[2][3] = {{1, 2, 3}, {4, 5, 6}};
	// Loop: repeat while the condition holds
	for (int row = 0; row < 2; row++) {
		// Loop: repeat while the condition holds
		for (int col = 0; col < 3; col++) {
			// Print to the console with cout
			std::cout << grid[row][col] << " ";
		}
	}
	// Print to the console with cout
	std::cout << std::endl;
	// Return 0 to signal that the program finished successfully
	return 0;
}

अलग Bounds वाले Nested Loops

एक nested pair में outer और inner loops को matching bounds की ज़रूरत नहीं, और inner loop की bound outer loop के current variable पर भी depend कर सकती है, जो यह है कि बढ़ते या सिकुड़ते patterns कैसे produce होते हैं।

उदाहरण: Nested Loops with Different Bounds

cpp

// Include std::cout and std::cin
#include <iostream>

// Program execution starts in main()
int main() {
	// Loop: repeat while the condition holds
	for (int i = 1; i <= 3; i++) {
		// Loop: repeat while the condition holds
		for (int j = 1; j <= i; j++) {
			// Print to the console with cout
			std::cout << "* ";
		}
		// Print to the console with cout
		std::cout << std::endl;
	}
	// Return 0 to signal that the program finished successfully
	return 0;
}

Nested Loops की Performance

एक nested loop में iterations की total संख्या outer और inner loop counts का product है, इसलिए बड़ी ranges पर nested loops जल्दी costly हो सकते हैं, performance के बारे में सोचते समय एक important consideration।

उदाहरण: Performance of Nested Loops

cpp

// Include std::cout and std::cin
#include <iostream>

// Program execution starts in main()
int main() {
	// Declare outerCount and set it to 100
	int outerCount = 100;
	// Declare innerCount and set it to 100
	int innerCount = 100;
	long totalIterations = (long)outerCount * innerCount;
	// Print to the console with cout
	std::cout << "Total iterations: " << totalIterations << std::endl;
	// Return 0 to signal that the program finished successfully
	return 0;
}

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