CODEWITHSUNDEEP
c++
packetie
packetie

Reputation: 5069

make C++ treat unsigned char* as char*

I inherit c++ source files with lots of calls to x.append(p, len), where x is of string type. However, in many cases, p is of type "unsigned char *" it caused lots of errors on my g++ (ver 4.8.4). If I manually change the p to (char*)p, it will work. But there are too many such instances (poor me!).

Wonder if there is a way to tell g++ just treat unsigned char* as char *.

Thanks.

UPDATE 1

The following code snippet will give an error when compiling with command line g++ -std=c++11 -fpermissive te1.cc. However, it actually compiles (fine but with a warning) when the type of variable len is changed from int to size_t. Unfortunately I can't change the type of the parameter, wonder if there is a way to tell compiler to just treat the second parameter as size_t when searching for a version of append() method.

//content of te1.cc
#include <iostream>

typedef unsigned char uchar;
using namespace std;
string x = "hi ";

int main(int argc, char *argv[]) {
    uchar *p = (uchar *)"tom";
    int len = 3;
    x.append(p, (size_t)len);
    cout << x << endl;
    return 0;
}

Upvotes: 1

Views: 271

Answers (2)

D&#250;thomhas
D&#250;thomhas

Reputation: 10048

Good grief! Don't hack stuff like that!

If you really must change the default signedness of char, use the proper GCC command-line option:

  • -funsigned-char
  • -fsigned-char

However, it would be better to simply fix the code to use the proper type at declaration, and deal with the (few) odd spots where something breaks.

Upvotes: 0

Radek
Radek

Reputation: 846

EDIT:

Extending c++ string class probably isn't a good idea (see that question).

I don't know in what contexts in your code the append method is used, but You may try to add type casts using your favorite editor and a simple regular expression:

Find pattern:

append\(([^,\)]+),([^\)]*)\);

Replace pattern:

append((char *)($1),$2);

See the small example I made.

Upvotes: 1

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