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Boolean variables in C

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• How to define boolean variables in C if C does not have a boolean data type ?

  • How to define a boolean type variable in C:

    If you need a boolean variable, define an int type variable instead

    Because:

    Compare operators ( < , <= , > , >= , == , != ) and logical operators ( && , || , ! ) returns 0 or 1, we can store the result of these operations in an int typed variable

    Example: the Bubblesort in C

    #include <stdio.h> #include <stdbool.h> int main( int argc, char* argv[] ) { int Done; // int var pretending to be a Boolean variable int k; int Help; int N = 10; int A[10] = {10, 5, 7, 8, 2, 1, 4, 3, 6, 9}; // Array, discussed later /* ------------------------------------------------------ Bubble Sort code from pj7 ------------------------------------------------------ */ Done = false; // *** Use boolean variable k = 1; while ( ! Done ) { Done = true; // *** Use boolean variable for (int i = 0; i < N-k; i++) { if (A[i] > A[i+1]) { Help = A[i]; A[i] = A[i+1]; A[i+1] = Help; Done = false; // Not sorted... } } k = k + 1; } }

    Output:

    10 5 7 8 2 1 4 3 6 9 1 2 3 4 5 6 7 8 9 10

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  • Example Program: (Demo above code)                                                
    • Prog file: /home/cs255001/demo/C/set1/logic3.c

    How to run the program:

    To compile:   gcc logic3.c          To run: ./a.out