How to pass string to a function in C

Question

Suppose I have a string "hello". I want to pass it to a function

void fun(char *p)
{
printf("%s",*p);
}

int main()
{
fun("hello");
}

Example 2 :

How do I pass a character to char * ?

void fun(char *p)
{
printf("%s",*p);
}
int main()
{
char a = 'c';
fun(a);
}

Why is this not working?

How to pass a string to a function in c without passing its address

Second one : `fun(a);` => `fun(&a);` and **keep** the `*` in the print. Change the format `printf("%c",*p);`Read the dupe for explanation. — 0___________, May 16 '21 at 09:44
@0___________ `&a` cannot be used as a string because there are no terminating null-character. — MikeCAT, May 16 '21 at 09:44
in 'fun(a)' a is a 'char' and you don't dereference it while printing. — thirdeye, May 16 '21 at 09:55
@thirdeye I want to type cast a character to character array ? Is it possible to do? — Aman Jain, May 16 '21 at 09:56
@0___________ I just wanted to pass a character to char [] is it possible?/ — Aman Jain, May 16 '21 at 09:59
[Cast char to char array or char array to char?](https://stackoverflow.com/questions/4687587/cast-char-to-char-array-or-char-array-to-char) if this help. — thirdeye, May 16 '21 at 10:00

score -1 · Answer 1 · answered May 16 '21 at 09:40

-1

The code doesn't work because %s accepts the pointer to the string, but an integer is passed. printf() may think that the integer is the pointer, but actually there are almost no chance that the integer becomes a valid pointer.

printf("%s",*p); invokes undefined behavior because char is passed where char* is expected. You should remove * here. Also p should be const char* instead of char* to tell the compiler that the string is not modified.

void fun(const char *p)
{
printf("%s",p);
}

To pass strings (sequences of characters terminated by a null-character) without passing its address, you can put strings in structures and pass them.

#include <stdio.h>

struct str_container {
    char str[32];
};

void fun(struct str_container sc)
{
    printf("%s",sc.str);
}

int main(void)
{
    struct str_container str = {"hello"};
    fun(str);
    return 0;
}

answered May 16 '21 at 09:40

MikeCAT

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how do I pass a character to char pointer? Like my example 2 – Aman Jain May 16 '21 at 09:42
@AmanJain "pass a character to `char *`" is ambiguous. Do you want to pass a string or simply a pointer to a character? – MikeCAT May 16 '21 at 09:43
my program generates a char which I further want to redirect to a function having char*\ – Aman Jain May 16 '21 at 09:54
I want to pass a string – Aman Jain May 16 '21 at 09:58

How to pass string to a function in C

1 Answers1