Boolean Type of C Language

No boolean type is defined in the C language standard (c89). Therefore, when the C language determines whether the true or false is true, 0 is false, and non-0 is true. Therefore, we usually use logical variables:

// Defines an int type variable. If the variable value is 0, it indicates false, and if the value is 1, it indicates true.
Int flag;
Flag = 0;
//......
Flag = 1;

If (FLAG)
{
//......
}

　　

However, this method is not intuitive, and it is not clear that the flag must be a Boolean value. Therefore, we use the macro definition in C language:

// Macro defines the Boolean Type
# Define bool int
# Define true 1
# Define false 0

// Define a Boolean variable
Bool flag = false;

 

Although this method is intuitive, it is still a form of change. The variable flag is still of the int type in the compiler.

The new version will always improve some disadvantages, so the latest C language standard (c99) solves the Boolean Type problem. C99 provides the _ bool type, so the boolean type can be declared as _ bool flag.

_ Bool is still an integer type, but unlike general integer types, _ bool variables can only be assigned 0 or 1 values, and non-0 values are stored as 1.

C99 also provides a header file <stdbool. h> that defines bool AS _ bool, true as 1, and false as 0. You only need to import stdbool. h to operate the Boolean Type conveniently.

// Import stdbool. h to use the Boolean Type
# Include <stdbool. h>
# Include <stdio. h>

// Calculate n !, The value of N is defined in main.
Int main (void)
{
Int n = 10; // calculate the stacked Multiplier
Int sum = 1; // It is used to store the result of the stacked multiplication.
Bool flag = false; // stacked multiplication mark
    
Int num = N; // number of cycles
While (! Flag)
{
Sum = sum * (Num --);
// End the loop when num = 1
If (num = 1)
{
Flag = true;
}
}
Printf ("% d's stacked multiplication value is % d \ n", N, sum );
Return 0;
}