printing c string pointer

Question

I am having problems when it comes to printing/displaying a char *string

This is my string

    char *messageForServer = ("netsvr type0 dobrien %s- %s",inet_ntoa(clientAddr.sin_addr),port);

and when I go to print it like

printf("%s\n",messageForServer);

it will only print the port part of the string. Will be greatfull for any help as it is bugging me for hours and cant seem to find an answer

Maybe you should show some sample output, and explain how this differs from what you want.. — Ron, Nov 17 '14 at 20:18

score 1 · Accepted Answer · edited May 23 '17 at 10:26

You should do it like this:

char messageForServer[100];
sprintf(messageForServer, "netsvr type0 dobrien %s- %s", "something", "8080");
printf("%s\n", messageForServer);

UPD: which prints the following

netsvr type0 dobrien something- 8080

The reason why your code doesn't work is - well, the way you try to get a formatted string has nothing to do with string formatting in C. See Creating C formatted strings (not printing them) for more information.

ryyker · Answer 2 · 2014-11-17T20:34:58.833

In C, a char * can be created and initialized by assigning a string literal:

char *string = {"some text here"};

It will not understand the initializer you tried,

("netsvr type0 dobrien %s- %s",inet_ntoa(clientAddr.sin_addr),port);

for at least two reasons: 1) because it contains more than a literal string, and 2), the ( ) enclosures are syntactically wrong (use { } instead).

If you want to create a string comprised of more than simple text (i.e. a string literal), say for example a string comprised of two strings, an integer and a float, you can do it this way:

char string[NUM_CHAR];

sprintf(string, "%s %d %s %f", "Example of string with ", 4, "elements, including the float:", 3.15);

score 0 · Answer 3 · answered Nov 17 '14 at 20:27

I think what you're trying to do here is provide a reusable function to print a "message for server" at various points in your code. You might consider doing exactly that: define a messageForServer() function as opposed to your attempt at a pre-formatted string.

void messageForServer(char *msg, char *code)
{
    printf("netsvr type0 dobrien %s - %s\n", msg, code);
}

Simple. Clean. Reusable.

printing c string pointer

3 Answers3