[Warning] passing arg 1 of `strcmp' makes pointer from integer without a cast

Code:

---

#include <stdio.h>
int main(){
    int a=15 ;
    int  b =20 ;
    strcmp((a, "20") == 0) {
    printf("Correct!");
    }
    else {
        printf("noooooooooooooo!");
        }
    fflush(stdin);
    getchar();
      }

---

result : [Warning] passing arg 1 of `strcmp' makes pointer from integer without a cast:mad:

can someone explain to me the error message please and how to fix it , thank you :)

Code:

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    strcmp( (a, "20") == 0 ) { /* Added spacing */

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Do you see your mistake now?

Secondly, please do NOT call fflush() on stdin, that results in undefined behavior. You can only call fflush() on output streams and even then you only need to do it if you don't use a \n or receive input after printing.

Quote:

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Originally Posted by nonpuz

Code:

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    strcmp( (a, "20") == 0 ) { /* Added spacing */

---

Do you see your mistake now?

Secondly, please do NOT call fflush() on stdin, that results in undefined behavior. You can only call fflush() on output streams and even then you only need to do it if you don't use a \n or receive input after printing.

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sorry I dont see the mistake

You cannot use strcmp to compare a number and a string. They either both have to be numbers or they both have to be strings. If they're both string, then you can use strcmp().

Quote:

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Originally Posted by whiteflags

You cannot use strcmp to compare a number and a string. They either both have to be numbers or they both have to be strings. If they're both string, then you can use strcmp().

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I changed to strcmp((a,b) == 0)
and still the same

Quote:

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Originally Posted by fouzimedfouni

I changed to strcmp((a,b) == 0)
and still the samep

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That is because you are still making the same mistake, except that now you made it twice. The type of a and b is int. strcmp is declared as:

Code:

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int strcmp(const char *s1, const char *s2);

---

Clearly, int is not compatible with const char*. In this case, strcmp looks entirely unnecessary. You could have written:

Code:

---

#include <stdio.h>

int main(void) {
    int a = 15;
    int b = 20 ;
    if (a == b) {
        printf("Correct!");
    } else {
        printf("noooooooooooooo!");
    }
    getchar();
    return 0;
}

---

Note that if you do want to call strcmp, you should #include <string.h>

Quote:

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Originally Posted by laserlight

That is because you are still making the same mistake, except that now you made it twice. The type of a and b is int. strcmp is declared as:

Code:

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int strcmp(const char *s1, const char *s2);

---

Clearly, int is not compatible with const char*. In this case, strcmp looks entirely unnecessary. You could have written:

Code:

---

#include <stdio.h>

int main(void) {
    int a = 15;
    int b = 20 ;
    if (a == b) {
        printf("Correct!");
    } else {
        printf("noooooooooooooo!");
    }
    getchar();
    return 0;
}

---

Note that if you do want to call strcmp, you should #include <string.h>

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ok here is the new code, it compile no error but when I type 15 it doesnt work as it supposed to

Code:

---

#include <stdio.h>
#include <string.h>
int main(void)
{
    char a[] = "15";
    char  b[1];
    printf("enter the secret word : ");
    scanf("%d",b);
   
   
    if(strcmp(a,b) == 0)
    {
        printf("Correct!");
    }
    else
    {
        printf("noooooooooooooo!");
    }
   
    fflush(stdin);
    getchar();
    return 0;
}

---

Quote:

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Originally Posted by fouzimedfouni

I changed to strcmp((a,b) == 0)
and still the same

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Of course it is still the same.

Do you know about comparisons?

>	greater than operator (a > b)
<	less than operator (a < b)
>=	greater than or equal to operator (a >= b)
<=	less than or equal to operator (a <= b)
==	equal to operator (a == b)
!=	not equal to operator (a != b)

Strings are a special case - they cannot be compared lexicographically with these operators, so the strcmp() function was created and standardized to do that. As I indicated earlier, if they are both strings, then you can use strcmp(). If they are different types, like one is a number, and the other is a string, than nothing will help you. In C, you can only make a comparison between EITHER numbers or strings.

so strcmp() does compare with INT too ?

Quote:

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Originally Posted by fouzimedfouni

so strcmp() does compare with INT too ?

---

No, it does not and it never will. For numbers, you need to pick one of the comparison operators.

If I am presuming something wrong, I apologize, but I think there is much confusion about types that is the root of the problem.

Let's turn what you want to do into a function:

Code:

---

void CompareFunc (int a, char b[])
{
 
    if( ??? )
    {
        printf("Correct!");
    }
    else
    {
        printf("noooooooooooooo!");
    }
}

---

The problem is, this function takes a number and a string. There isn't a way to directly compare a number and a string in C, though. You can turn the variable a into a string, and then compare with strcmp, or you can turn the variable b into a number and then compare with operators (not strcmp()).

C does have ways to do either of these things, so the resolution can be simple. Please read:
http://faq.cprogramming.com/cgi-bin/...&id=1043284385
http://faq.cprogramming.com/cgi-bin/...043284385#opt3

Quote:

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Originally Posted by whiteflags

No, it does not and it never will. For numbers, you need to pick one of the comparison operators.

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thank you so much, I really appreciate your answer I see it now :)

Incidentally, with an array of just one character, the only string you can store in it is an empty string. If you want to read an int with scanf using the %d format specifier, then you should be passing a corresponding pointer to int as an argument to scanf, not a pointer to a char.