Adding an integer to a C-string

[duragezic]

I don't know. I can't think of how to do this. It must be very simple.

I have an integer variable holding some number, say from 1 to 50, that gets incremented with each new message.

Currently, I store a copy of some C-strings combined into a single C-string as an element in an array of C-strings using strcat().

For example, I have

char *msg1 = "this is"
char *msg2 = "a msg"

then I do

strcat(messages[idx], msg1)
strcat(messages[idx], msg2)

so then messages[idx] reads "this is a msg"

But I want to use that integer variable so that the element in 'messages' reads

"i: this is a msg"

where i is the actual value of that integer variable. I see some string to double or integer functions in string.h, and this would all be much easier with a C++ String, but I don't know.. I'm just not finding a way to do this. Any ideas?

 

[Aikouka]

Use itoa:

http://www.cplusplus.com/reference/clibrary/cstdlib/itoa.html

Or you could just do all the casting work yourself .

 

[duragezic]

It says its a non-standard function supported by only some C compilers.

I have included <stdio.h> and <stdlib.h> for other things I needed already, but there's a compiler error of

main.o(.text+0x2a1): In function `storeCmd':
/major/swcarlso/cs4411/project1/main.c:130: undefined reference to `itoa'


So the compiler I have to use doesn't support it?

 

[Madwand1]

sprintf or a variation?

 

[clamum]

Try sprintf or whatever that function is that lets you format printing to standard out.

 

[you2]

To be safe you want snprintf (not that it is relevant to your program). man snprintf should tell you everything you need to know...

 

[xtknight]

Yeah, using strcat is a waste of time when you have functions like sprintf. Its counterpart snprintf prevents buffer overflows if used properly. (strncat is the safe strcat version.)

sprintf(targetvar, "%d: %s", 5, "here is a string");

targetvar will then be: "5: here is a string\0"

 

[EagleKeeper]

char buffer[255]
sprintf (buffer,%d: %s %s",value,msg1, msg2);