10 replies to this topic

[jackson6612]

Hi

Is this true when an int or a float is converted into a bool, "0" or "0.0" is converted into "0" and anything else (e.g. 2, 9, -1, 1.9, 0.0003, 0.4, -0.8) is converted into "1". Could you please confirm this? Thanks.

[WingedPanther]

Which language are you talking about? C and C++ handle this differently.

[jackson6612]

C++

[Alexander]

You need to understand that 0.0 is not 0. The former is a floating point numeric and is not automatically cast to zero by assigning it to a boolean type. 0.0 will therefor become true not false.

Any value other than 0 (of any integral type, i.e. char, short, integer or long) will be true and you can assume this. -1, 0.0, 1.0 are all true.

[jackson6612]

Alexander said:

You need to understand that 0.0 is not 0. The former is a floating point numeric and is not automatically cast to zero by assigning it to a boolean type. 0.0 will therefor become true not false.

Any value other than 0 (of any integral type, i.e. char, short, integer or long) will be true and you can assume this. -1, 0.0, 1.0 are all true.

Thanks. Sorry for asking this if the answer is already too obvious! Non-integral type will also be true such as 0.0001, -0.09.

Regards
Jackson

[jackson6612]

jackson6612 said:

Thanks. Sorry for asking this if the answer is already too obvious! Non-integral type will also be true such as 0.0001, -0.09.

Is my statement correct? Please let me know. Thanks.

[Alexander]

jackson6612 said:

Is my statement correct? Please let me know. Thanks.

Yes, integral types would represent only whole numbers (i.e. no fractions).

[fayyazlodhi]

In addition c does not have a bool data type and uses int with 0 and non zero values in all places such as if for and while.

C++ does have a bool type that has been referred to above.

Also you can write code such as

    float a = -0.009;


    if((bool)a == false)

        printf("false\n");

    else

        printf("true\n");

to verify it yourself. It is casting a float to a bool and checking resulting value.

[jackson6612]

fayyazlodhi said:

In addition c does not have a bool data type and uses int with 0 and non zero values in all places such as if for and while.

C++ does have a bool type that has been referred to above.

Also you can write code such as

    float a = -0.009;


    if((bool)a == false)

        printf("false\n");

    else

        printf("true\n");

to verify it yourself. It is casting a float to a bool and checking resulting value.

Hi Fayyaz

I think you have your code in C. I have changed it into C++. There was no need to convert "a" into bool in the if condition because the if statement already uses the bool type for comparison and automatic conversion takes place. Do I have it correct? Please let me know. Thanks a lot.

 #include <iostream>

 #include <cstdlib>


 using namespace std;


 int main()


 {


    float a = -0.009;


   [B] if(a == false)[/B]

        cout << "false\n";

    else

        cout << "true\n";


    system("pause");


    return 0;

 }

[fayyazlodhi]

yes you are right. I only added the cast to make it more explicit so that you know what is happening by seeing it in code rather than knowing that "in an if condition it automatically converts into bool".

[jackson6612]

Thank you for letting me know this, Fayyaz.