c language help - concate

Johny12345
Johny12345 used Ask the Experts™
on
Hi,

I am newbie c language learner. Please let me know how can I define a string and concatenate some integer values with string and print it too. I also need to send that string data to a server using a API.

I tried below but it shown strange characters in print and I guess it will send same strange characters when I sent it to server using API. Please guide.

thx

char str[200];
int q,w,e;
strcpy (str," ");
		strcat (str,"X:");
	   	strcat (str,q);
		strcat (str," Y:");
		strcat (str,w);
		strcat (str," Z:");
		strcat (str,e);
	
	sprintf("Data: '%s'\n", str); // show strange characters...

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You cannot cat an integer directly. You could use sprintf to create the entire string.
http://www.cplusplus.com/reference/cstdio/sprintf/?kw=sprintf
You already know how to use %s to include a string. Here is their sample program that demonstrates how to include integers in the buffer.
/* sprintf example */
#include <stdio.h>

int main ()
{
  char buffer [50];
  int n, a=5, b=3;
  n=sprintf (buffer, "%d plus %d is %d", a, b, a+b);
  printf ("[%s] is a string %d chars long\n",buffer,n);
  return 0;
}

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Commented:
thx for your reply. I need your more help. Please let me know what happens at:

char buffer [50];      // You have defined character with max limit of 50 characters

  int n, a=5, b=3;    // defined 3 integers

  n=sprintf (buffer, "%d plus %d is %d", a, b, a+b);  
// what will be value of n and what will be value of buffer
// Also, you have defined n as int so how it can help string??

  printf ("[%s] is a string %d chars long\n",buffer,n);

Please reply soon.

thx
>> what will be value of n and what will be value of buffer
>> Also, you have defined n as int so how it can help string??
What helps the string is buffer - it contains the entire string that is output by the sample program.
Return Value
On success, the total number of characters written is returned. This count does not include the additional null-character automatically appended at the end of the string.
 On failure, a negative number is returned.
I would put the sample program and write out the value of n to make sure you agree with the documentation.
The output of the sample program is:
[5 plus 3 is 8] is a string 13 chars long

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>> char buffer [50];      // You have defined character with max limit of 50 characters
Not 50 characters; only 49, since one byte is needed for the string's terminating null byte.

For n, the int return value, you should test for an error condition since "On failure, a negative number is returned".
I'll be back in less than 24 hours to see if you have any follow up questions.

Paul

Author

Commented:
thanks

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