CODEWITHSUNDEEP
c++
user1686630
user1686630

Reputation: 109

How to parse a char array into a double

Here is my question, I created char temp[100] to store the numbers in a file, the temp_i is the index of current position(the numbers has temp_i digits)

How to convert the char array temp from 0 to temp_i into the value I created?

Can any body help me?

stack<int> first;
char temp[10]={'0','0','0','0','0','0','0','0','0','0'};
int temp_i = 0;
bool isDouble = false;
for(int index = 0; index< strlen(str); index++){
    if(str[index] != ' '){
      temp[temp_i++] = str[index];
    } 
    else if(str[index] == '.') {
      isDouble = true;
     } else {
       double value = *(double*)temp;
       cout<<value<<endl;
       first.push(value);
      }
}

Upvotes: 1

Views: 1965

Answers (3)

Thomas Matthews
Thomas Matthews

Reputation: 57678

If you allocated one more slot in your array and assigned it to '\0', you could treat your character array a C style string.

The C-style string opens up a whole bunch of library routines, such as std::strtod and std::sscanf which can assist you.

You could also use std::istringstream to get your double.

Upvotes: 2

Jules Gagnon-Marchand
Jules Gagnon-Marchand

Reputation: 3781

Use sstream.

#include<sstream>
#include<iostream>
using namespace std;

int main()
{
    char * str = "123.4567 813.333   999.11";
    stringstream converter;

    converter<<str<<str<<str;


    double number0;
    double number1;
    double number2;

    converter>>number0;
    cout<<number0<<endl;

    converter>>number1;
    cout<<number1<<endl;

    converter>>number2;
    cout<<number2<<endl;


    cin.ignore('\n', 100000);

    return 0;
}

Returns :

123.4567
813.333
999.11

Upvotes: 0

Jules Gagnon-Marchand
Jules Gagnon-Marchand

Reputation: 3781

Atof (ascii to float) does pretty much exactly what you are trying to do.

It takes a pointer to a null ended string and returns a float.

You just have to cut your main string with all your numbers into one string per number, but that should be pretty easy with something like stringstream.

Upvotes: 0

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