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# How to use boolean type in C?

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Question:

C does not have the boolean data type by default. Is there a way by which we can implement it?

In C language, we do not have the boolean datatype by default. That means we cannot do something like

if(true)
{
// perform some commands
}
else
{
// perform the else commands
}


We can do this in C++ and JAVA. However, we have an alternative method to achieve the same functionality. Before moving on to the implementation it is important to know that in C, if a value is ‘0 (zero)’ it is treated as false, and any other value other than ‘0’, is treated as true.
That means if we do something like

if(2)
{
// THIS PORTION WILL RUN
}
else
{
// this will NOT
}

if(0)
{
// this will NOT RUN
}
else
{
// THIS PORTION WILL RUN
}

while(1)
{
// an example of an infinite loop
}


Thus, to implement the boolean data type we can do it by 3 methods:-

Method 1:-

typedef int bool;
#define true 1
#define false 0


Method 2:-

typedef int bool;
enum { false, true };


Method 3:-

typedef enum { false, true } bool;


All 3 methods, basically perform the same functionality. It assigns the value ‘1’ to true and ‘0’ to false. This way we define a custom data type. and the C pre-processor takes care of the rest of the stuff.

Here is a sample program that illustrates the use of this custom boolean datatype in C.

#include<stdio.h>

//defining the boolean datatype
typedef int bool;
#define TRUE 1
#define FALSE 0

//defining the main function to test
int main(void)
{

//testing the methodology
if(FALSE)
{
printf("I CANT PRINT");
}
else
{
printf("YOU SUCCESSFULLY IMPLEMENTED boolean DATATYPE");
}

//An example of infinite loop
while(TRUE)
{
printf("This loop will run forever");
}

return 0;
}


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