How can I use strcat_s with two strings to print in one line?

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I want to use strcat_s() funciton to combine two string in one line. For example users enter his\her name and his\her job. the console print name-job:

Please enter your name:Rahsan
Please enter your job:Engineer

Rahsan-Engineer

But console print Rahsan
-Engineer.

How can I fix this problem?

What I have tried:

#include <locale.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

int main()
{
	setlocale(LC_ALL, "Turkish");
	char name[20];
	char job[20];
	char users[40]="";

	printf("Please enter your name:\n");
	fgets(name, sizeof(name), stdin);
	printf("\n");
	printf("Please enter your job:\n");
	fgets(job, sizeof(job), stdin);
	printf("\n");

	strcat_s(users,40,name);
	strcat_s(users,40,"-");
	strcat_s(users,40,job);
	puts(users);
	
	return 0;
}

Posted 27-Jun-20 4:53am

goksurahsan

Updated 27-Jun-20 5:48am

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2 solutions

Solution 2

fgets() includes the newline at the end of the string (assuming the input has not been truncated), so you need to trim off the trailing newline. There's several ways to do that, here's two:

C

fgets(name, sizeof(name), stdin);

/* Method one, using strlen() */
size_t len = strlen(name);
if(name[len] == '\n')
   name[len] = '\0';

/* method two, use strchr */
char *ptr = strchr(name, '\n');
if(ptr != NULL)
    *ptr = '\0';

You should be aware that fgets() does not flush the input buffer, so if the user enters "Arnold Schwarzenegger" (length 21 chars), you'l end up with

C

name = "Arnold Schwarzenegg";
job="er"

. To get around this you could use getline()

C

size_t len = 0;
char *input = NULL;
ssize_t rlen;

rlen = getline(&input, &len, stdin);
/* rlen is the number of chars read in, so we can trim the newline without calling
   another function */
if(rlen > sizeof(name) { /* read in too many chars */
    input[sizeof(name)-1] = '\0'; /* effectively make input only 19 chars long */ 
else if(rlen > 0)  { /* trim off trailing newline */
    input[rlen-1] = '\0';
else {
    /* do error handling */
}
strcpy(name, input); /* safe, since we already trimmed input if over-length */

/* ... */
free(buff);

When using getline() the second parameter, len in the above example, is the size of the input buffer that has been allocated by getline(). You don't need to free and reset the input buffer between calls to getline(). The second parameter to getline is the size of the allocated input buffer, so if you need to read several lines you only need to call free() after your last use of the input buffer. This also means that getline() will only reallocate the buffer as it needs to.

Posted 27-Jun-20 5:48am

k5054

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OriginalGriff · Accepted Answer · 2020-06-27T05:16:00

For starters, your output area is too small: the two arrays you are reading from the user are 20 characters each, and you add a "-" in the middle. You need to ensure that the output buffer is big enough to hold all the data you want to fit in it.

The problem you see is that the fgets function leaves the newline at the end of the string it reads - so when you print it it prints the newline from teh name, then the hyphen and the job title.

Add a function to remove it:

C++

void Trim(char* str)
{
	char* pos;
	if ((pos = strchr(str, '\n')) != NULL)
	{
		*pos = '\0';
	}
}

Then just call it twice:

C++

printf("Please enter your name:\n");
fgets(name, sizeof(name), stdin);
printf("\n");
Trim(name);
printf("Please enter your job:\n");
fgets(job, sizeof(job), stdin);
printf("\n");
Trim(job);

If you had used the debugger, you would have seen why it happens pretty much immediately ... I'd strongly suggest you get familiar with the debugger, it's th' most useful tool you have available to you!