I get this error: "invalid operands of types 'const char*' and 'const char [6]' to binary 'operator+'" when i try to compile my script. Here should be the error:
string name = "john"; system(" quickscan.exe resolution 300 selectscanner jpg showui showprogress filename '"+name+".jpg'"); The type of expression
" quickscan.exe resolution 300 selectscanner jpg showui showprogress filename '"+name+".jpg'" is std::string. However function system has declaration
int system(const char *s); that is it accepts an argumnet of type const char *
There is no conversion operator that would convert implicitly an object of type std::string to object of type const char *.
Nevertheless class std::string has two functions that do this conversion explicitly. They are c_str() and data() (the last can be used only with compiler that supports C++11)
So you can write
string name = "john"; system( (" quickscan.exe resolution 300 selectscanner jpg showui showprogress filename '"+name+".jpg'").c_str() ); There is no need to use an intermediate variable for the expression.
std::string + const char* results in another std::string. system does not take a std::string, and you cannot concatenate char*'s with the + operator. If you want to use the code this way you will need:
std::string name = "john"; std::string tmp = "quickscan.exe resolution 300 selectscanner jpg showui showprogress filename '" + name + ".jpg'"; system(tmp.c_str()); As all the other answers show, the problem is that adding a std::string and a const char* using + results in a std::string, while system() expects a const char*. And the solution is to use c_str(). However, you can also do it without a temporary:
string name = "john"; system((" quickscan.exe resolution 300 selectscanner jpg showui showprogress filename '"+name+".jpg'").c_str()); The addition of a string literal with an std::string yields another std::string. system expects a const char*. You can use std::string::c_str() for that:
string name = "john"; string tmp = " quickscan.exe resolution 300 selectscanner jpg showui showprogress filename '"+name+".jpg'" system(tmp.c_str()); The system function requires const char *, and your expression is of the type std::string. You should write
string name = "john"; string system_str = " quickscan.exe resolution 300 selectscanner jpg showui showprogress filename '"+name+".jpg'"; system(system_str.c_str ());