Conditional Operator in C and C++

Conditional Operator is an operator which is substitutive for if-else statements. It is a ternary operator (operator which operates on 3 operands). It is often called ?: operator. The operands are expression1, expression2 and expression3. The syntax is as follows:

expression1 ? expression2 : expression3

The expression expression1  will be evaluated always. Execution of expression2 and expression3 depends on the outcome of expression1. expression1 is checked whether true or not. It is considered like a boolean variable. The outcome of an expression is true if it has a non zero value. If its value is zero, the outcome of expression is false. If the expression1 is true, then expression2 is evaluated. If the expression1 is false, then expression3 is evaluated. Consider the following example:

Sizeof operator in C

Sizeof operator is a unary operator used in both C and C++ programming languages. This operator is used to get the size of a data type, variable, object of a class, structure variable etc in bytes. In some programs it may be necessary to use the size of certain variable or data type. Such situations often occur in file handling programs. But the size of data type may vary from machine to machine. In most of the 32 bit systems, int has a size of 4 bytes. But in some systems it is 2 bytes. So, if a program is written by assuming the size to be known, it will affect the portability of the program since a change in size of a data type may result in unexpected output. In such cases, the sizeof operator helps to obtain the size of data type or variable in bytes. The argument of sizeof can be a variable of primitive days types (int, char etc), an object (of class), a structure variable, union variable, pointer variables etc. The sizeof operator is very useful in dynamic memory allocation.

C program to show working of sizeof operator:

#include<stdio.h>

struct student

{

char name[5];

int roll;

int mysize;

};

main()
{
unsigned long int b;
printf("size of variable b: %d",sizeof b);
printf("\nsize of int:%d",sizeof(int));
printf("\nsize of float:%d",sizeof(float));
printf("\nsize of char:%d",sizeof(char));
printf("\nsize of long:%d",sizeof(long));
printf("\nsize of double:%d",sizeof(double));
printf("\nsize of short:%d",sizeof(short));
struct student s1;
s1.mysize=sizeof(s1.name)+sizeof(s1.roll)+sizeof(s1.mysize);
printf("\nSizeof structure student :%d",s1.mysize);
/*see the difference shown in size of structure */
printf("\nsize of structure student : %d",sizeof(struct student));
}

Output: