Problem with strcat() function

**sureshkumarct** · 01-01-2007

I want to create an html file using C and as the first step , I wrote a simple program as follows:

Code:

#include<stdio.h>
#include<conio.h>
#include<string.h>
void main()
{
char *name="My Namel",*str="";
clrscr();
strcat(str,"<html><head>");
strcat(str,name);
strcat(str,"</html></head>");
puts(str);
getch();
}

But the puts(str) statement is giving unexpected result.What is getting printed is "<html><head>My Name Name ad>". Why doesnt it print "<html><head>My Name </html></head>" as is expected? .Ultimately I want to write the string str to the html file using file operation. I tried adding a null character at the end of str, but that throws some illegal operations exceptions and Turbo C is terminated ubruptly.Thanks in advance

**Bajanine** · 01-01-2007

first of all it is: int main

You need to allocate memory for the string. Look up malloc and free.

/edit.
Or for something simple like this you could just make your string as big as it needs to be. The trouble is determining how big you need it to be without wasting all kinds of space.

Code:

char str[80];  /* this let you store up to 80 chars including the null. */

/edited for code tags and...
You should look up "strncat" especially if you go the quick and dirty method of using a fixed length array for your strings.

/edit 3
conio.h is not a standard header.

**ssharish2005** · 01-03-2007

Code:

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

int main()    // main should return a value
{
    char *name="My Namel";
    /* If this is the string that u are concatenating. This should had enough
    space to hold the string which u are about to concatenate
    
    Ex: str1 = "hello"
        str2 = "world"
        
        char str3[15];
        
        strcat(str1,str2); --> "helloworld\0"; // this is how it will represent
    */
    char str[80]; 
    
    strcpy(str,"<html><head>");
    strcat(str,name);
    strcat(str,"</head></html>");
    
    fputs(str,stdout);
    
    getchar();
    return 0;
}

/* my output
<html><head>My Namel</head></html>
*/

you need proper code indentation.

NOTE: To be more dynamic u can use malloc to allocate space for str at runtime. Which u might have to look in the future

ssharish2005

**dwks** · 01-03-2007

Why are you flushing sdout before you print anything? Why are you flushing it at all? . . . getchar() will flush it for you.

You output is wrong. The first call should be strcpy(), not strcat(), or else you should set set[0] to '\0'.

**ssharish2005** · 01-03-2007

DWKS, just concentrating on his code. I Don't know i was checking it, for some reason i places flushed it out but forgot to remove it out. Any way thanks for that

ssharish2005

**dwks** · 01-03-2007

Well if you were checking it why did you miss the first strcat()?

BTW, fputs() doesn't output a newline like puts() does.

You should look up "strncat" especially if you go the quick and dirty method of using a fixed length array for your strings.

http://www.cplusplus.com/reference/c...g/strncat.html

> Turbo C
*gasp*
.
.
.
You should strongly consider getting a newer compiler, such as Dev-C++.

**Dave_Sinkula** · 01-03-2007

Yet another way.

Code:

#include <stdio.h>

int main(void)
{
   char str[80], name[] = "My Namel";
   sprintf(str, "<html><head>%.*s</head></html>", (int)(sizeof str - 27), name);
   fputs(str, stdout);
   getchar();
   return 0;
}

/* my output
<html><head>My Namel</head></html>
*/

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