Adding an int into middle of char* (In C)

Question

Was wondering how it were possible to have an int in the middle of a char*, as such:

char * winning_message =
"Congratulations, you have finished the game with a score of " + INT_HERE +
"                 Press any key to exit...                   ";

`char *` + INT_HERE is valid. result is also `char *`. but `char *` + `char *` is invalid. So, It isn't possible. — BLUEPIXY, Sep 08 '17 at 04:13
It might be ok in the sense that it would compile, but I don't think it would yield the behavior the questioner is trying to achieve. — Jeremy Friesner, Sep 08 '17 at 04:19
@BLUEPIXY I was referring to the 'char * + INT_HERE', which, as you say, is valid, but as I say, doesn't yield the result the questioner wants (the resulting pointer would, at best, point to the end-part of the string, rather than to a string with an integer interposed) — Jeremy Friesner, Sep 08 '17 at 20:30

score 3 · Answer 1 · answered Sep 08 '17 at 04:14

3

Perhaps you are looking for something like this?

char buf[256];  // make sure this is big enough to hold your entire string!
sprintf(buf, "Congratulations, you have finished the game with a score of %i\nPress any key to exit...", INT_HERE);

Note that the above is unsafe in the sense that if your string ends up being longer than sizeof(buf), sprintf() will write past the end of it and corrupt your stack. To avoid that risk, you could call snprintf() instead:

char buf[256];  // make sure this is big enough to hold your entire string!
snprintf(buf, sizeof(buf), "Congratulations, you have finished the game with a score of %i\nPress any key to exit...", INT_HERE);

... the only downside is that snprintf() may not be available on every OS.

answered Sep 08 '17 at 04:14

Jeremy Friesner

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You should use snprintf if you use fixed length buffers. – bukkojot Sep 08 '17 at 04:16
Yes, I covered that in my answer. – Jeremy Friesner Sep 08 '17 at 04:22
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"`snprintf()` may not be available on every OS"-- note that `snprintf()` is a Standard Library function, and so must be available in any conforming implementation. – ad absurdum Sep 08 '17 at 04:39

score 1 · Accepted Answer · answered Sep 08 '17 at 04:14

1

With this:

char winning_message[128]; // make sure you have enough space!
sprintf(winning_message, "Congratulations, you have finished the game with a score of %i. Press any key to exit...", INT_HERE);

answered Sep 08 '17 at 04:14

Jas

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You should use snprintf if you use fixed length buffers. – bukkojot Sep 08 '17 at 04:17

bukkojot · Answer 3 · 2017-09-08T04:18:06.907

1

You can use:

char * winning_message;
asprintf(&winning_message,"Congratulations, you have finished the game with a score of %d\nPress any key to exit...\n", INT_HERE);

edited Sep 08 '17 at 04:18

answered Sep 08 '17 at 04:15

bukkojot

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Note that with asprintf() you will need to call free(winning_message) after you are done with the string, or else your program will leak memory. – Jeremy Friesner Sep 08 '17 at 04:17
`asprintf()` is not a Standard Library function, or even a POSIX funtion, but a compiler extension. – ad absurdum Sep 08 '17 at 04:41
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@DavidBowling library extension – Antti Haapala -- Слава Україні Sep 08 '17 at 05:33

Adding an int into middle of char* (In C)

3 Answers3