Add Day 14: Array of array, Typecasting, Scopes in C

Author: sahilbansal17

Day 14/README.md

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+## Programs for Day 14
+
+1. [Understand array of arrays](arrayOfArrays.c)
+2. [Implicit Typecasting](typecasting.c)
+3. [Explicity Typecasting](avgOfThreeNumbers.c)
+4. [Constants in C][constant.c]
+5. [Macros](macros.c)
+6. [Static variables](staticVariable.c)

Day 14/arrayOfArrays.c

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+/*
+ * Program to print month name given the number (1-12)
+ * using array of arrays concept in C
+ */
+
+#include <stdio.h>
+
+int main () {
+
+	// month_name is an array of arrays
+	// it can have different length strings in each row
+	char *month_names[] = {
+		"January", "February", "March", "April", "May",
+		"June", "July", "August", "September",
+		"October", "November", "December" };
+	printf("Please enter the month no (1-12): ");
+	int month_no;
+	scanf("%d", &month_no);
+
+	// check for validity of the input
+	if (month_no >= 1 && month_no <= 12) {
+		printf("Month is: %s\n", month_names[month_no - 1]);
+	} else {
+		printf("Invalid input\n");
+	}
+
+	return 0;
+}

Day 14/avgOfThreeNumbers.c

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+/*
+ * Program to compute avg of three numbers
+ */
+
+#include <stdio.h>
+
+int main () {
+
+	int num1, num2, num3;
+	scanf("%d %d %d", &num1, &num2, &num3);
+		
+	double avg = (double) (num1 + num2 + num3)/3;
+	printf("Average of these numbers is: %f\n", avg);
+	return 0;
+}

Day 14/constant.c

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+/*
+ * Program to understand constants in C
+ */
+
+#include <stdio.h>
+
+// #define PI 3.141
+
+int main () {
+
+	const float PI = 3.141;
+	// float const PI = 3.141;
+	int radius = 3;
+
+	// PI = 3.14; // it will generator an error, that constant cannot be modified
+	float area = PI*radius*radius;
+	printf("Area: %f\n", area);
+	return 0;
+}

Day 14/macros.c

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+/*
+ * Program to understand macros in C
+ */
+
+#include <stdio.h>
+
+#define AREA(l, b) (l*b)
+#define sqr1(y) y*y
+#define sqr2(y) (y)*(y)
+
+int main () {
+
+	int l1 = 10, l2 = 5;
+	int area = AREA(l1, l2);
+	printf("Area: %d\n", area);
+	
+	int macro1Res = sqr1(5+3);
+	int macro2Res = sqr2(5+3);
+	printf("Square of (5+3) using\nMacro 1: %d\nMacro 2: %d\n", macro1Res, macro2Res);
+	return 0;
+}

Day 14/staticVariable.c

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+/*
+ * Program to understand the static variables in C
+ */
+
+
+#include <stdio.h>
+
+/* Function declaration */
+void display();
+
+int main() {
+    
+    display();
+    display();
+    display();
+    // printf("Can we access n2: %d\n", n2);
+    return 0;
+}
+
+/* Function definition */
+void display() {
+    int n1 = 10;
+    // value of a static variable persists across different function calls
+    static int n2 = 10;
+
+    printf("Local n1 = %d, Static n2 = %d\n", n1, n2);
+
+    n1++; // Increment local variable
+    n2++; // Increment static variable
+}
+

Day 14/typecasting.c

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+/*
+ * Program to understand typecasting in C
+ */
+
+#include <stdio.h>
+
+int main () {
+	char ch = 'A';
+	int res = ch + 10;
+	printf("res: %d\n", res);
+	return 0;
+}