CODEWITHSUNDEEP
cpointers
Ravi
Ravi

Reputation: 31397

copy string in c using pointer

Code copy string in C

#include <stdio.h>
char *copyString(char *,char *);
void main()
{
    char *first = (char *)calloc(sizeof(char),10);
    char *second = (char *)calloc(sizeof(char),10);
    printf("Enter first string:\t");
    scanf("%s",first);
    printf("%s",copyString(first,second));
}
char *copyString(char *a,char *b)
{
    int i=0;
    while(*(a+i)!='\0')
    {
        *(b+i)=*(a+i);
        i++;
    }
    *(b+i)='\0';
    return b;
}

Case 1:

Input : Hello

Output : Hello

Case 2:

Input : Hello World

Output : Hello

So, my question is whether space is considered as newline/null ?? Because, in second case, it shows like this..

Upvotes: 1

Views: 6678

Answers (7)

Aniket Inge
Aniket Inge

Reputation: 25695

scanf() stops reading after the first whitespace by default. Use fgets() or gets()[unsafe]. With regards to why it is this way, you might want to read the POSIX pages here: http://www.unix.com/man-page/POSIX/3posix/scanf/ and ISO C standards here: http://www.open-std.org/jtc1/sc22/wg14/www/docs/n1124.pdf. It has a lengthy description on how scanf() and fscanf()(and all other standard C functions) should work. These are generally followed guidelines on how functions in C library should work.

All compilers strive hard to create POSIX compliant standard-c libraries that work the same across most UNIX'ish platforms.

The standard C functions are actually defined here: http://www.open-std.org/jtc1/sc22/wg14/www/docs/n1124.pdf

Upvotes: 2

usman mehmood
usman mehmood

Reputation: 112

use #include and utilize this function strcpy of string.h lib. following is the example:

    strcpy(first, second);

This should run fine.

Upvotes: 0

rharrison33
rharrison33

Reputation: 1282

The scanf function here will read input until it encounters whitespace. You will need to implement a readline function.

Upvotes: 0

Abubakkar
Abubakkar

Reputation: 15644

Your scanf is scanning just one string for two strings to be scanned you should write:

      scanf("%s %s",first,second);

Similarly for more strings to be scanned you should do like this that is giving as many %s as many strings you want to scan.

Upvotes: 0

iabdalkader
iabdalkader

Reputation: 17312

As suggested scanf stops at the first whitespace, you could use fgets instead to read the whole line. And when you get that working allocate more space, because "Hello World" is 12 bytes not 10.

Upvotes: 1

P.P
P.P

Reputation: 121377

It's because stops reading after whitespace when you input it the string. So you actaully only have "Hello" in your first string, not "Hello world".

Use fgets() to read the whole line.

Upvotes: 1

md5
md5

Reputation: 23699

By default, scanf stops reading the standard input stream when a space character ' ' is encountered. To fix it, you can use a scanset.

scanf("%[^\n]", first);

Upvotes: 9

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