Convert octal string to decimal string in C++

Question

What is the easiest way to convert string holding octal number into string holding decimal representation of the same number?

I could convert it into int value using strtol, then convert into string again using stringstream:

string oct_number("203"); 

// converts into integer
int value = strtol(oct_number.c_str(), NULL, 8);

// converts int to decimal string
stringstream ss;
ss  << value;
string dec_number = ss.str();

But: is there any quicker way to do it? I have a rather poor understanding of the stringstream class, am I missing something?

Vlad from Moscow · Accepted Answer · 2014-02-02 22:15:24Z

2

std::string result;
Try
{
   result = std::to_string( std::stoi( oct_number, 0, 8 ) );
}
catch ( ... )
{
//...
}

answered Feb 2, 2014 at 22:15

Vlad from Moscow

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4 Comments

David G Over a year ago

He said he wanted to convert it to decimal so shouldn't it just be std::stoi(oct_number)?

Vlad from Moscow Over a year ago

@0x499602D2 He wants to convert one string into another string.

David G Over a year ago

He said he wanted the decimal representation if I'm not mistaken.

Vlad from Moscow Over a year ago

@0x499602D2 Read his post one more. It is clear enough.

Alex Telishev · Accepted Answer · 2014-02-02 22:11:01Z

0

In c++11 you can use string dec_number = to_string (value);. Also you can use sprintf but you will need some buffer:

char buf[64];
sprintf(buf,"%d",value);
string dec_number = buf;

answered Feb 2, 2014 at 22:11

Alex Telishev

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