CODEWITHSUNDEEP
clinuxpointersstruct
user3691561
user3691561

Reputation: 31

C Code compiled failed in Linux Debian

I'm currently writing C program, I'm using struct and pointer in the functions. Everything works well in Windows, but not linux debian. I'm having some errors when I try to compile my program in Linux Debian.

typedef struct human
{
char name[100],code[100];
}human;

void hello(char* name, char* code)
{}

int main()
{
human human;
hello(&human.name,&human.code);
return 0; 
}

I get those warning when compiling the main.c file:

Warning passing argument 1 of Human from incompatible pointer type
Note: expected char *a but argument is type of char(*)[100]
Warning passing argument 2 of Human from incompatible pointer type
Note: expected char *a but argument is type of char(*)[100]

Upvotes: 0

Views: 67

Answers (2)

0xF1
0xF1

Reputation: 6116

The error basically means that you are passing address of an array to a function which expects a char array.

The type of human.name is char [100] i.e. char array of size 100. When you pass it as human.name to the function, it decays into base address of that array which has type char*. So, everything fine, and you actually wanted this behavior only.

Now, you tried to pass &human.name, which means you are trying to pass address of human.name array to the function, which is of type char (*) [100] (a pointer to char array of size 100), and hence the type mismatch occurs.

Upvotes: 0

Jonathon Reinhart
Jonathon Reinhart

Reputation: 137398

typedef struct human
{
    char name[100], code[100];
} human;

void hello(char* name, char* code)
{
}

int main()
{
    human human;
    hello(human.name, human.code);
    return 0; 
}

Remove the ampersands (&) when passing the name and code arrays. A char array is compatible with char*. When you say human.name, you're really referring to the address of the first element in the array.

Also, if hello doesn't return anything, its return type should be void. If you omit the return type, int is assumed, but this is a very old practice, and highly discouraged.

You should always use at least -Wall when compiling with GCC. Best practice (which you should get used to sooner rather than later) is:

gcc -Wall -Wextra -Werror foo.c

Finally, use proper indentation!

Upvotes: 4

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