This topic is now archived and is closed to further replies.


double to char conversion

Recommended Posts

Specchum    242
Wouldn''t it be easier if you tried it out first? It only takes 3 or 4 lines of code! Besides, there is nothing like seeing the result for yourself and interpreting the result.

"There is no dark side of the moon." - Pink Floyd

Share this post

Link to post
Share on other sites
BlueDev    126

Well I have seen from experience that trying to choose which of the three codes, gcvt() , ecvt() , and fcvt() can be difficult.

I recommend gcvt() in this case. I'm not sure you are handling scientific notations, "ecvt() " or "fcvt() ", so we will stick with "gcvt() ".

Now I wrote a sample code that converts a double floating point to a string, and back, using the standard library functions. I also used atof() to convert a string back to a floating point. Of course you might think that a double is not the same as a float. Well in all cases you see the names are different, only thing that is different with the double is it supports 32-bit, while float 24 or 16, and integer 8.

#include <stdio.h>
#include <stdlib.h>

int main() {
char buffer[50];
int precision = 5;
double value = 245.92;

// Convert to string

gcvt(value, precision, buffer);
printf("%s\n", buffer);

// Convert back to double

value = atof(buffer);
printf("%f\n", value);

return 0;
Example 1.1: Converting a double to string and vice-versa using gcvt() and atof()

Alright, well the example is simple and well explained. I'll just explain up on gcvt() .

· The first parameter handles the value , others say the floating point (double in this case). It retrieves whatever is stored in this data type variable.
· The second parameter, precision , tells the function how many numbers it is going to convert. For instance, if precision were 3 in this example all that would convert is "245", else if precision were 4 the outcome would be "245.9", and so on and so forth.
· The third parameter, of course, needs a buffer to write too. So you just seed one to it and it automatically writes the info in your string.

I hope this has helped,

[edited by - BlueDev on March 23, 2004 11:41:25 AM]

Share this post

Link to post
Share on other sites
ChaosEngine    5185
or better yet if you're using C++

#include <string>
#include <sstream>

int main()
double x = 23.3;
std::stringstream str;

str << x << std::ends;

std::string result = str.str();


"That's not a bug, it's a feature!"

[edited by - ChaosEngine on March 23, 2004 8:14:36 PM]

Share this post

Link to post
Share on other sites
hello_there    122
one more question what''s the biggest number a char can hold? Is it 0 - 255 since the biggest number 1 byte can hold is 11111111 which is 255. also how does a char or any other type store if the number is negative?

Share this post

Link to post
Share on other sites