[Error] invalid conversion from 'int' to 'const char*' [-fpermissive]

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[Error] invalid conversion from 'int' to 'const char*' [-fpermissive]
The above error occurs when I try to run the following code:

C

#include<stdio.h>
int main()
{
	int a = 10;
	int * ptr;
	ptr=&a;
	printf(ptr);
	printf("\n");
	printf(* ptr);
	printf("\n");
	printf(*(*(ptr)));
}

Thanks,
regards,
yeskay.

What I have tried:

I just declare a pointer variable and assigns the address of another variable. I try to print it. But I get this error:

[Error] invalid conversion from 'int' to 'const char*' [-fpermissive]

Posted 8-Feb-22 15:02pm

Santhana Krishnan 2022

Updated 9-Feb-22 10:55am

Sean Ewington

v3

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CPallini 9-Feb-22 2:01am

C is not Python...

1 solution

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k5054 · Accepted Answer · 2022-02-08T16:20:00

You need to review how printf() is used: printf, fprintf, sprintf, snprintf, printf_s, fprintf_s, sprintf_s, snprintf_s - cppreference.com[^]
In general printf() looks like

C

int printf(const char *format_string,  arg1, arg2, ...);

Where format_string describes the other arguments. So for example a format string of "%d" will treat the next argument as a integer, regardless of what it actually is. It is up to you, as the programmer to get things right. Fortunately, these days compilers are "printf aware" and can usually spot a problem and issue warnings as needed.
In your case you have

C

int *ptr;
printf(*ptr);

The warning you are getting is telling you that you are trying to convert the value of *ptr, which is an int with value 10 to a pointer type (char *), so its as if you wrote

C

printf(10)

10 is not a character string, so the compiler is letting you know that something is not right.