What is the void keyword in C?
The literal meaning of void is empty or blank. In C, void can be used as a data type that represents no data.
Usage
In C, void can be used as:
Return typeof a function that returns nothing. Consider the code snippet below, which usesvoidas a return type.
#include<stdio.h>void sum(int a, int b){printf("This is a function that has no return type \n");printf("The function prints the sum of its parameters: %d", a + b);}int main() {sum(2, 5);return 0;}
Input parameterof a function that takes no parameters. Consider the code snippet below, which usesvoidas an input parameter.
#include<stdio.h>int foo(void){printf("This is a function that has no input parameters \n");return 0;}int main() {foo();return 0;}
Note: In C,
foo()is different fromfoo(void).foo()means that the function takes an unspecified number of arguments.foo(void)is used for a function that takes no arguments.
Generic pointerdeclaration that has no type specified with it. Consider the code snippet below, which usesvoidas a pointer declaration.
#include<stdio.h>int main() {int a = 1;char b = 'B';float c = 3.3;void * ptr = &a;int *a2 = (int*) ptr;printf("The number is: %d \n", *a2);ptr = &b;char *b2 = (char*) ptr;printf("The character is: %c \n", *b2);ptr = &c;float *c2 = (float*) ptr;printf("The float is: %f \n", *c2);return 0;}
Note: The
voidpointer cannot be dereferenced directly. It has to be type cast to a data type before being dereferenced.
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