CODEWITHSUNDEEP
c++
XanderLynn
XanderLynn

Reputation: 883

C++ signed char to double

I am new to C++ and am having an issue converting a signed char to a double. Initial idea was to convert the signed char to a const char* and use atof to return the double.

signed char x = '100';
const char * cChar = x;
std::cout << atof(cChar);

What can I try to resolve this?

Upvotes: 0

Views: 2440

Answers (5)

Tommy
Tommy

Reputation: 100602

It should just be:

double value = static_cast<double>(x);

What you're currently doing is creating a pointer to memory address 100, which you almost certainly don't own, then attempting to read a string from there, which almost certainly isn't there.

(note: I originally suggested the C-style version, double value = (double)x;, see the comments below as to why C-style casts are better avoided in C++)

Upvotes: 0

Gareth A. Lloyd
Gareth A. Lloyd

Reputation: 1942

I'm trying to get my head around what your current understanding is

signed char x = '100';

This line of code is taking the character '100' which doesn't exist, typically characters are one symbol long such as 'a' and '9'. Unless they are special non printable sequences such as null '\0' or newline '\n', or even escaped characters such as single quote'\''

C style string are represented by double quotations and have one hidden byte at the end that hold a null terminator, the double quote notation deals with the null for you.

if your looking to convert the string "100" to a double then the following will work

double a;
char b [4] = "100";
a = atof(b);

Upvotes: 0

yasouser
yasouser

Reputation: 5177

You might want to use strtod() or you can use boost::lexical_cast<>

Upvotes: 1

Erik
Erik

Reputation: 91260

signed char x = 100;
double d = x;
cout << d;

const char * x = "100";
double d = atof(x);
cout << d;

'100' is wrong - you need either a const char * x = "100"; or a char x=100;

Upvotes: 2

paperjam
paperjam

Reputation: 8498

Or do you mean

const char *x = "100";
std::cout << atof(x);

?

Upvotes: 1

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