Add Day 7: Jump statements

Author: sahilbansal17

Day 6/nestedLoops.c

@@ -1,6 +1,6 @@
 /*
  * Program to print multiplication table
- * of numbers from 1 to 10 
+ * of numbers from 1 to 5 (generalized to n)
  * using nested loops.
  */
 
@@ -9,10 +9,12 @@
 int main () {
 
 	/*
-		1 2 3 4  5  6  7  8  9  10
-		2 4 6 8  10 12 14 16 18 20
-		3 6 9 12 15 18 21 24 27 30
-		4 ...
+		1  2  3  4  5  
+		2  4  6  8  10 
+		3  6  9  12 15
+		4  8  12 16 20
+		..
+		10 20 30 40 50
 	*/
 
 	// what are we looping on?
@@ -24,5 +26,35 @@ int main () {
 	// outer loop: we loop on the i-th multiple (i=1 to 10)
 	// inner loop: all numbers 
 
+	/* 
+		pseudo code:
+		
+		// outer loop
+		for (multiple = 1 to multiple = 10) {
+			// inner loop
+			for (number = 1 to number = 5) {
+				print(number*multiple)
+			}
+		}
+
+	*/
+
+	int n;
+	scanf("%d", &n);
+
+	// outer loop takes care of all the multiples from 1 to 10
+	for (int multiple = 1; multiple <= 10; multiple ++) {
+
+		// inner loop takes care of all numbers from 1 to n
+		// %4d in the printf means that for the integer which
+		// is to be replaced by %d, the amount of space
+		// is fixed, i.e. 4 characters
+		for (int number = 1; number <= n; number ++) {
+			printf("%4d", number * multiple);
+		}
+
+		printf("\n");
+	}
+
 	return 0;
 }

Day 7/README.md

@@ -0,0 +1,10 @@
+## Break, continue and goto
+1. [Example program to understand break](break.c)
+2. [Example program to understand continue](continue.c)
+3. [Example program to understand goto](goto.c)
+
+## Usage of break
+1. [Check whether given number is prime](prime.c)
+
+## Creating your own functions
+1. [Sum of first n prime numbers](sumOfNPrimes.c)

Day 7/break.c

@@ -0,0 +1,40 @@
+/*
+ * Program to understand usage of break statement
+ * inside loops.
+ */
+
+#include <stdio.h>
+
+int main () {
+
+	// break during second iteration of the loop
+	/*
+	for (int i = 0; i < 10; i ++) {
+		if (i == 1) {
+			break;
+		}
+		printf("%d ", i);
+	}
+	*/
+
+	for (int multiple = 1; multiple <= 10; multiple ++) {
+		for (int number = 12; number <= 16; number ++) {
+			if (number == 15) {
+				break;
+			}
+			printf("%4d", number * multiple);
+		}
+
+		printf("\n");
+	}
+
+	// break just inside if is useless
+	/*
+	int n = 5;
+	if (n == 6) {
+		break;
+	}
+	*/
+	
+	return 0;
+}

Day 7/continue.c

@@ -0,0 +1,29 @@
+/*
+ * Program to understand usage of continue statement
+ * inside loops.
+ */
+
+#include <stdio.h>
+
+int main () {
+
+	// sum of even numbers from 1 to n
+
+	int n;
+	scanf("%d", &n);
+
+	int sum = 0;
+	for (int number = 1; number <= n; number ++) {
+		// number is odd
+		if (number % 2 == 1) {
+			continue;
+			// if the above line is executed,
+			// rest of the loop is skipped
+			// and we move to next iteration
+		} 
+		sum += number;
+	}
+
+	printf("%d\n", sum);
+	return 0;
+}

Day 7/goto.c

@@ -0,0 +1,30 @@
+/*
+ * Program to understand usage of goto
+ */
+
+#include <stdio.h>
+
+int main () {
+
+	for (int i = 0; i < 10; i ++) {
+		for (int j = 0; j < 10; j ++) {
+			for (int k = 0; k < 10; k ++) {
+				for (int l = 0; l < 10; l ++) {
+
+					// requirement:
+					// you want to terminate all the loops
+					// when i = 5, j = 5, k = 5, l = 5
+
+					if (i == 5 && j == 5 && k == 5 && l == 5) {
+						// break; this will just terminate the inner loop
+						goto end;
+					}
+
+				}
+			}
+		}
+	}
+
+	end:
+	return 0;
+}

Day 7/prime.c

@@ -0,0 +1,41 @@
+/*
+ * Program to check whether number input from the user
+ * is a prime number or not!
+ */
+
+#include <stdio.h>
+
+int main () {
+
+	int number;
+	scanf("%d", &number);
+
+	// we need to check whether the number is a prime or not
+	// prime no. is the one which has only 1 and the number
+	// itself as its divisors
+
+	// ex: n = 2, 3, 5, 7, 11, 13, 17, ...
+
+	// there are infinitely many primes!!!
+
+	// Shubham's idea:
+	// we can start a loop of 'divisor' from 2 to n/2, 
+	// if the number is divisbile by divisor => no. is not prime
+	// why do we check only till n/2, because
+	// a number n cannot be divided by number > n/2 except itself
+
+	int count = 0;
+	for (int divisor = 2; divisor <= number/2; divisor ++) {
+		if (number % divisor == 0) {
+			count ++;
+			printf("Number is not prime\n");
+			break;
+		}
+	}
+
+	if (count == 0) {
+		printf("Number is prime.\n");
+	}
+
+	return 0;
+}

Day 7/sumOfNPrimes.c

@@ -0,0 +1,49 @@
+/*
+ * Program to find sum of first n primes
+ */
+
+#include <stdio.h>
+
+// write our own functions
+// our first very own function to check whether a number is prime
+// syntax:
+/* functionReturnType functionName(paramterType paramterName, ...) {
+		function body;		
+   }
+*/
+
+int isPrime(int number) {
+	for (int divisor = 2; divisor <= number/2; divisor ++) {
+		if (number % divisor == 0) {
+			return 0;
+		}
+	}
+	return 1;
+}
+
+int main () {
+
+	int n;
+	scanf("%d", &n);
+
+	int result = 0; // to store the sum of the primes
+	int currentNumber = 2; // current number being checked for prime
+	int countedPrimes = 0; // no of primes already counted
+	while (countedPrimes < n) {
+		// if current number is prime
+		//   add the current no. to result if it's a prime
+		// increase the current no.
+
+		// how do we call a function?
+		// functionName(function Parameters)
+		if (isPrime(currentNumber) == 1) {
+			result += currentNumber;
+			countedPrimes ++;
+		}
+
+		currentNumber ++;
+	}
+
+	printf("%d\n", result);
+	return 0;
+}