Thread: Storing the output of printf into a string

Hello

I have a procedure that gets an md5sum result and prints it out to console. How can I get the results into a string?


This is what I am looking for

Code:

string get_md5_sum(unsigned char* md) {
    string retval = "";
    int i;
    for(i=0; i <MD5_DIGEST_LENGTH; i++) {
            printf("%02x",md[i]);
            retval += md[i];         ////// this is not right because I have to convert it via %02x,  how do i do this?
    }

    return retval;
}

This is my full code

Code:

#include <sys/types.h>
#include <sys/stat.h>
#include <sys/mman.h>
#include <iostream>
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <string>
#include <openssl/md5.h>


using namespace std;


unsigned char result[MD5_DIGEST_LENGTH];


void print_md5_sum(unsigned char* md) {
    int i;
    for(i=0; i <MD5_DIGEST_LENGTH; i++) {
            printf("%02x",md[i]);
    }
}


void get_md5_sum(unsigned char* md) {
    int i;
    for(i=0; i <MD5_DIGEST_LENGTH; i++) {
            printf("%02x",md[i]);
    }
}


// Get the size of the file by its file descriptor
unsigned long get_size_by_fd(int fd) {
    struct stat statbuf;
    if(fstat(fd, &statbuf) < 0) exit(-1);
    return statbuf.st_size;
}


int main()
{
    int file_descript;
    unsigned long file_size;
    char* file_buffer;


    string sFilePath = "myfilepath";


    file_descript = open(sFilePath.c_str(), O_RDONLY);
    if(file_descript < 0) exit(-1);


    file_size = get_size_by_fd(file_descript);
    printf("file size:\t%lu\n", file_size);


    MD5((unsigned char*) file_buffer, file_size, result);
    print_md5_sum(result);


    string sIn;
    cin >> sIn;


    return 0;
}

Thanks in advance.

Then you can use the std::hex manipulator on the stream too.

Thank you for the replys, I dont know if it is the lack of sleep or what but it still prints garbage

Code:

string get_md5_sum(unsigned char* md)
{
    stringstream ss;
    for(int i = 0; i <MD5_DIGEST_LENGTH; i++)
    {
        printf("%02x",md[i]);
        ss << std::hex << md[i];
    }
    return ss.str();
}

Code:

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

const int MD5_DIGEST_LENGTH = 10;

std::string get_md5_sum(unsigned char* md) {
    std::stringstream ss;
    for(int i = 0; i < MD5_DIGEST_LENGTH; i++)
        ss << std::setw(2) << std::setfill('0') << std::hex
           << static_cast<unsigned>(md[i]);
    return ss.str();
}

int main() {
    unsigned char s[] = "\x01\x02\x11\x12\x88\x99\xaa\xbb\xcc\xdd";
    std::cout << get_md5_sum(s) << '\n';
    return 0;
}