Problems calling system() in c++

Question

I tried to use system() in a c++ app it works very well if i do it like:

system("notepad");

But it gives error when i try to do like:

cin >> cmdlol;  
system(cmdlol);

Error:

cannot convert 'std::string {aka std::basic_string}' to 'const char*' for argument '1' to 'int system(const char*)'|

Note that reading a string in and passing it to `system` is a massive security risk. — TartanLlama, May 19 '16 at 09:18
@TartanLlama why would be? Is bash (or any shell) a massive security risk? After all, all it does is "reading a string in and passing it to `system`"... — el.pescado - нет войне, May 19 '16 at 09:43

score 11 · Accepted Answer · edited May 19 '16 at 12:13

11

cmdlol seemes to be std::string, which can't be converted to const char* implicitly. And std::system only accepts const char* as its argument, that's why compiler complains.

You could use std::basic_string::c_str() explicitly.

system(cmdlol.c_str());

And about why system("notepad"); works well, "notepad" is a string literal with type const char[8] (including null character), note it's not std::string and might decay to const char* when passed to std::system.

edited May 19 '16 at 12:13

Pete Becker

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answered May 19 '16 at 09:08

songyuanyao

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Yay! It worked, thank you. I can accept this answer in 11mins because new question. – Mudzay May 19 '16 at 09:09

score 4 · Answer 2 · answered May 19 '16 at 09:09

4

std::system wants a const char*, that's a C-style array.

To convert a std::string to a const char*, you can use the function c_str().

system(cmdlol.c_str());

answered May 19 '16 at 09:09

Rakete1111

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Problems calling system() in c++

2 Answers2