variables and data types

data-types-variables.c

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+/**
+ * @file data-types-variables.c
+ * @author kunal jain ([email protected])
+ * @brief Simple functions to test data types, 
+ *        constants and ternary operator.
+ * @version 0.1
+ * @date 2022-02-17
+ * 
+ * @copyright Copyright (c) 2022
+ * 
+ */
+#include<stdio.h>
+
+// Function to show overflow of char datatype
+// When you declare a variable in C, by default
+// it is a signed data type.
+void test_datatype_overflow() {
+    // signed char - 8 bits
+    char c = 127;
+    printf("Value of c -> %d\n", c);
+
+    // overflows at 127
+    // Value goes to negetive extreme 
+    // after overflow
+    c = 128;
+    printf("Value of c -> %d\n", c);
+
+    // underflows at -128
+    // Value goes to positive extreme 
+    // after underflow
+    c = -129;
+    printf("Value of C -> %d\n", c);
+}
+
+// Function to show sizeof()
+// sizeof(data-type) -> Function returns size of 
+//                      data type in bytes.
+// sizeof() Argument -> variable name or data type
+void test_datatype_size() {
+    // sizeof() with explicit data type as argument
+    printf("Size of char -> %d\n", sizeof(char));
+    printf("Size of integer -> %d\n", sizeof(int));
+
+    // sizeof() with variable name as argument
+    short int i = 0;
+    printf("Size of i -> %d\n", sizeof(i));
+}
+
+// This function shows how to define octal and 
+// hexadecimal integer constants.
+void test_var_octal_hexa() {
+    // Leading 0 -> Octal value
+    int octal = 0123;
+    // Leading 0x -> hexadecimal value
+    int hexa = 0x123;
+    printf("Octal value in decimal -> %d\n", octal);
+    printf("Hexadecimal value in decimal -> %d\n", hexa);
+}
+
+// Enumeration constants
+// Value of Sunday -> 0
+//          Monday -> 1 ... and so on
+enum week { Sunday, Monday, Tuesday, Wednesday };
+
+// Values of Enum start from 0, unless explicitly defined.
+
+// Value of JAN -> 1 Explicitly defined
+//          FEB -> 2
+//          MAR -> 3 ... and so on
+enum months { JAN = 1, FEB, MAR, APR, JUN };
+
+// This function prints enum values.
+void test_enum() {
+    // Access enum value by declaring a variable 
+    // of enum type. Here day is of type enum week
+    enum week day;
+    day = Wednesday;
+    printf("Day -> %d\n", day);
+
+    // Access enum value directly using 
+    // name of enum element.
+    printf("Value of Jan -> %d\n", JAN);
+}
+
+// This function prints initial value of local
+// and static integer.
+void test_var_initialization() {
+    // Local int initializes with a garbage value
+    int local_var;
+    // Static int initializes with zero value
+    static int static_var;
+
+    printf("Value of local variable is -> %d\n", local_var);
+    printf("Value of static variable is -> %d\n", static_var);
+
+    // Remember to explicitly define local variables
+    // as they initialize with a garbage value.
+}
+
+// Function to show how ternary operator works
+void test_ternary_operator() {
+    int z, a = 5, b = 7;
+
+    // if (expr1) {
+    //     expr2;
+    // } else {
+    //     expr3;
+    // }
+
+    // If else way to evaluate max(a,b)
+    //
+    // if (a > b) {
+    //     z = a;
+    // } else {
+    //     z = b;
+    // }
+
+    // Ternary operator -> More concise if else
+    // expr1 ? expr2 : expr3
+    // If expr1 is true,
+    //      evaluate expr2
+    // else evaluate expr3
+
+    // Ternary operator way to
+    // evaluate max(a,b)
+    z = (a > b) ? a : b;
+    printf("Value of z -> %d\n", z);
+}
+
+int main(void) {
+
+    // This is driver function. We call all function
+    // from this driver function.
+
+    // Uncomment the function that you want to run
+    // and check the output for.
+
+    // test_datatype_overflow();
+    // test_datatype_size();
+    // test_enum();
+    // test_var_octal_hexa();
+    // test_var_initialization();
+    // test_ternary_operator();
+
+    return 0;
+}