how to copy array of string to dynamic array in c++

Question

i just want to copy array of string to dynamical array(using new operator) without using string.h of c++ how can i copying the array?

enter code here
const int LEN=3;
int n=15;
char*s1 ;
char *s[LEN]={"music","disc","soft"};
char (*str)[LEN]=new char[n][LEN];   //i want to copy s to  this array

i try to do something like this

for(int i=0; i<LEN ;i++){
     strcpy(str[i],s[i]);
}
for(int i=0; i<LEN ;i++)
      cout<<str[i]<<endl;

but it printing all the array in one Sequence, i think a problem with NULL terminator i don't no how to deal with

Missing const, unused variable s1, and obsolete comment... — Jarod42
– Jarod42, Commented Jan 2, 2015 at 23:15
Don’t use char* in C++, please. It just hurts, and 99% of the time, proper std::string is what you want. Also, please use std::vector (or maybe std::array), even if it means typing a little more. — Christopher Creutzig
– Christopher Creutzig, Commented Jan 2, 2015 at 23:17
The requirement is to do without using standard string class — Daniel Hailemichael
– Daniel Hailemichael, Commented Jan 2, 2015 at 23:31
@DanielHailemichael: Then change the requirement. Writing C++ in the style of C is a recipe for heartache and pain. — Mike Seymour
– Mike Seymour, Commented Jan 2, 2015 at 23:56

Jarod42 · Accepted Answer · 2015-01-02 23:54:31Z

1

You invert the dimension of str, try:

const int LEN = 3;
const int n = 15;
const char *s[LEN] = {"music", "disc", "soft"};
char (*str)[n] = new char[LEN][n];

for(int i = 0; i < LEN ; i++) {
    strncpy(str[i], s[i], n);
}
for(int i = 0; i < LEN ; i++)
    std::cout << str[i] << std::endl;

delete []str;

Live example

answered Jan 2, 2015 at 23:54

Jarod42

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Community · Accepted Answer · 2017-05-23 12:05:53Z

1

Look at vector.

string sArray[3] = {"aaa", "bbb", "ccc"};
vector<string> sVector;
sVector.assign(sArray, sArray+3);

Source from here

edited May 23, 2017 at 12:05

CommunityBot

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answered Jan 2, 2015 at 23:17

Thellimist

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Mooing Duck · Accepted Answer · 2015-01-03 01:51:48Z

1

Sane C++ code would use vector or array, and also string. However, without those, pure C would often use a dynamic array of dynamic strings:

char** strs = new char*[LEN];  //a dynamic array of dynamic strings
//Alternatively, char* (*strs)[LEN]
for(int i=0; i<LEN; ++i) {
    strs[i] = new char[strlen(s[i])];
    strcpy(strs[i], s[i]);
}
//code goes here
for(int i=0; i<LEN; ++i) 
    delete[] strs[i];
delete[] strs;
strs = NULL;

However, your code is closer to a dynamic array of fixed length strings:

char **strs = new char[n][LEN];  //a dynamic array of dynamic strings
//Alternatively, char(*strs)[LEN][n], or is it char(*strs)[n][LEN]?
for(int i=0; i<LEN; ++i) 
    strcpy(strs[i], s[i]);
//code goes here
delete[] strs;
strs = NULL;

edited Jan 3, 2015 at 1:51

answered Jan 2, 2015 at 23:36

Mooing Duck

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