Question

How to copy a string in C++

Answer 1

// Copy using std::string assignment

#include <iostream>
#include <string>

int main() {
    std::string src = "Programming is fun";
    std::string dest = src;

    std::cout << dest << std::endl;
}



/*
run:

Programming is fun

*/

 

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Answer 2

// Copy using std::string constructor

#include <iostream>
#include <string>

int main() {
    std::string src = "Programming is fun";
    std::string dest(src);

    std::cout << dest << std::endl;
}



/*
run:

Programming is fun

*/

 

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Answer 3

// Copy using assign()

#include <iostream>
#include <string>

int main() {
    std::string src = "Programming is fun";
    std::string dest;

    dest.assign(src);

    std::cout << dest << std::endl;
}



/*
run:

Programming is fun

*/

 

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Answer 4

// Copy using strcpy (C-style)

#include <iostream>
#include <cstring>

int main() {
    const char* src = "Programming is fun";
    char dest[64] = "";

    std::strcpy(dest, src);

    std::cout << dest << std::endl;
}



/*
run:

Programming is fun

*/

 

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Answer 5

// Copy using strncpy (C-style)

#include <iostream>
#include <cstring>

int main() {
    const char* src = "Programming is fun";
    char dest[64] = "";

    std::strncpy(dest, src, sizeof(dest) - 1);
    dest[sizeof(dest) - 1] = '\0';

    std::cout << dest << std::endl;
}



/*
run:

Programming is fun

*/

 

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Answer 6

// Copy using memcpy

#include <iostream>
#include <cstring>

int main() {
    const char* src = "Programming is fun";
    char dest[64] = "";

    std::memcpy(dest, src, std::strlen(src) + 1);

    std::cout << dest << std::endl;
}



/*
run:

Programming is fun

*/

 

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Answer 7

// Copy using manual loop

#include <iostream>

int main() {
    const char* src = "Programming is fun";
    char dest[64] = "";

    int i = 0;
    while ((dest[i] = src[i]) != '\0') {
        i++;
    }

    std::cout << dest << std::endl;
}



/*
run:

Programming is fun

*/

 

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Answer 8

// Copy using pointer loop

#include <iostream>

int main() {
    const char* src = "Programming is fun";
    char dest[64] = "";

    char* d = dest;
    while ((*d++ = *src++) != '\0');

    std::cout << dest << std::endl;
}


/*
run:

Programming is fun

*/

 

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Answer 9

// Copy using std::copy

#include <iostream>
#include <algorithm>
#include <cstring>

int main() {
    const char* src = "Programming is fun";
    char dest[64] = "";

    std::copy(src, src + std::strlen(src) + 1, dest);

    std::cout << dest << std::endl;
}



/*
run:

Programming is fun

*/

 

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Answer 10

// Copy using snprintf

#include <iostream>
#include <cstdio>

int main() {
    const char* src = "Programming is fun";
    char dest[64] = "";

    std::snprintf(dest, sizeof(dest), "%s", src);

    std::cout << dest << std::endl;
}


/*
run:

Programming is fun

*/

 

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Answer 11

// Copy using stringstream

#include <iostream>
#include <sstream>
#include <string>

int main() {
    std::string src = "Programming is fun";
    std::stringstream ss;

    ss << src;
    std::string dest = ss.str();

    std::cout << dest << std::endl;
}



/*
run:

Programming is fun

*/

 

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