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Is enum signed or unsigned in C? I'm using Gcc to compile my program and I get 2 result with enum value as following code:

typedef enum test_e
{
    zero,
    one,
    two,
    three,
}test_t;

void compare_func(test_t var)
{
    printf("\n [1] my number is %d \n", var);

    if ( var > 0)
        printf(" %d > 0 \n", var);
    else if ( var < 0)
        printf(" %d < 0 \n", var);
}

typedef enum test_nega_e
{
    zero_nega,
    one_nega = -1,
    two_nega = -2,
    three_nega = -3,
}test_nega_t;

void compare_nega_func(test_nega_t var_nega)
{
    printf("\n [2] my number_nega is %d \n", var_nega);
    if ( 0 < var_nega)
        printf(" %d > 0 \n", var_nega);
    else if ( 0 > var_nega)
        printf(" %d < 0 \n", var_nega);
}

int main (void)
{
    test_t my_number;
    test_nega_t my_number_nega;

    my_number = -1;
    compare_func(my_number);

    my_number_nega = -1;
    compare_nega_func(my_number_nega);

    return 0;
}

And the result is: 

 [1] my number is -1 
 -1 > 0 

 [2] my number_nega is -1 
 -1 < 0

So "my_number" is unsigned and "my_number_var" is signed? Thanks

phuclv
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PaDuTo
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1 Answers1

0

You can't rely on an enum being either signed or unsigned.

See Are C++ enums signed or unsigned?

Mind that C and C++ enums are similar

Community
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Gabriel Vasconcelos
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