?
Solved

Copy of a string

Posted on 2011-03-05
5
Medium Priority
?
280 Views
Last Modified: 2012-05-11
Please tell me how I can make a copy of a given string, at run time.

If my function takes char *str as a parameter, then I want make a local copy of str within the function.

Thanks!
0
Comment
Question by:dshrenik
5 Comments
 
LVL 16

Expert Comment

by:Peter Kwan
ID: 35043582
0
 

Author Comment

by:dshrenik
ID: 35043593
I don't want to use library functions.

Will it work if I find the length of the string, then dynamically allocate a char array and assign its value to the original?

If possible, please provide some sample code.

Thanks!
0
 
LVL 16

Accepted Solution

by:
Peter Kwan earned 668 total points
ID: 35043670
You can do it this way (pseudo-code only):
char *new_str;
int i = 0;
new_str = (char*) malloc(sizeof(char));
new_str[i] = orig_str[i];
while (orig_str[i] != NULL) {
     new_str = (char*)realloc(new_str, (i+2)*sizeof(char));
     new_str[i] = orig_str[i];
     i++;
} 
new_str[i]=0;

Open in new window

0
 
LVL 11

Assisted Solution

by:Deepu Abraham
Deepu Abraham earned 668 total points
ID: 35044187
another way if implementing this . here is the snippet
char* strcpy_new(char* dest,const char* source)
{
	if ((dest == NULL)|| (source == NULL))
		return NULL;
        //if you know the length then you could check it here..
	int i = 0;
	while(source[i]!='\0')
	{
		dest[i] = source[i];
		i++;
	}
	if(dest[i] != '\0')
		dest[i] = '\0';

	return dest;
}

Open in new window

0
 
LVL 1

Assisted Solution

by:hogwell
hogwell earned 664 total points
ID: 35047085
// A simpler, more efficient version that creates a copy of the input string on the heap.
char* copy_a_string(const char *str)
{
    const char *str1=str;
    size_t len;
    char *copy_of_str;
    char *str2;
    while (*str1) ++str1;
    len = str1 - str;
    copy_of_str = (char*) malloc((len+1)*sizeof(char)); // Or use "copy_of_str = new char[len+1];" in C++
    for (str1=str,str2=copy_of_str; *str1; )
      *str2++ = *str1++;
    *str2 = '\0';
    return copy_of_string;
}
0

Featured Post

Free Tool: Path Explorer

An intuitive utility to help find the CSS path to UI elements on a webpage. These paths are used frequently in a variety of front-end development and QA automation tasks.

One of a set of tools we're offering as a way of saying thank you for being a part of the community.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Many modern programming languages support the concept of a property -- a class member that combines characteristics of both a data member and a method.  These are sometimes called "smart fields" because you can add logic that is applied automaticall…
Container Orchestration platforms empower organizations to scale their apps at an exceptional rate. This is the reason numerous innovation-driven companies are moving apps to an appropriated datacenter wide platform that empowers them to scale at a …
Video by: Grant
The goal of this video is to provide viewers with basic examples to understand and use nested-loops in the C programming language.
The goal of the video will be to teach the user the difference and consequence of passing data by value vs passing data by reference in C++. An example of passing data by value as well as an example of passing data by reference will be be given. Bot…
Suggested Courses

809 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question