I want to use static_cast to use string functions like erase() and find() in a character array, say char str[50]. For instance, please consider following segment:
char str[]="abcdefghi";
char val[]="bc";
static_cast<string>(str).erase(static_cast<string>(str).find(val[0]),1);
Please tell me if it is correct and if it is, then str is not retaining the value it should have, i.e. "acdefghi".
Please tell me if it is correct
It won't work.
static_cast<string>(str) will create a temporary std::string from str, its content is copied from str. Any modification on it has nothing to do with the original variable str.
You could do this on std::string, and convert it back to const char* when necessary.
string new_str(str); // construct std::string
new_str.erase(new_str.find(val[0]), )); // modification on it
cout << new_str.c_str() << endl; // convert back to `const char*`
find(val[0]) will do what you want. What do you mean ` char s[]=static_cast<string>(str).erase(static_cast<string>(str).find(val[0]),1);? You can't do that, std::string` can't be converted to char[] directly.If you want to access char* (raw c string) like an stl container this is std::experimental::string_view was invented for. But it will give an access only to read/iterate/find like operations, not modifying. There is also a sad moment - it is delayed for C++17 standard (anyway GCC-6.x already has it). See for boost::utility::string_view also. If you want to have modify access for char* I would recommend you using your own wrapper over string with length check, etc.
Here is an example I am talking about:
#include <iostream>
#include <experimental/string_view>
#include "string.h"
using namespace std;
typedef experimental::string_view string_view;
class RawStringWrapper : public string_view
{
char * sstr;
size_t len;
public:
RawStringWrapper(char * str, size_t sz)
: std::experimental::string_view(str, sz),
sstr(str),
len(sz){}
bool erase(const string &s){
auto pos = find(s);
if (std::string::npos != pos){
sstr[pos] = 0;
strcat(sstr, sstr + pos + s.size());
return true;
}
return false;
}
// ...other modifying functions you need
};
int main(int argc, char *argv[])
{
char rawString[] = "abcdefgh";
RawStringWrapper str(rawString, sizeof(rawString));
str.erase("cde");
cout << rawString << endl;
return 0;
}
