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This guideline is basically banning the use of std::string. Having a string abstraction beyond C null-terminated string is a huge deal both for convenience and

This guideline is basically banning the use of std::string. Having a string abstraction beyond C null-terminated string is a huge deal both for convenience and for safety. It is super easy to get strings wrong in C. This is also one of the reasons why printf won't work. You cannot pass a type like std::string to a variable args function.

hot_gril 2y ago
Was gonna say, this guide is too light on examples. So an example of string usage would be passing around null-terminated char arrays.
humanrebar 2y ago
std::string_view with %.*s as a string formatter work well enough if you're set on using printf.
- gpderetta 2y ago
  I have to use std::string_view with %.*s as a string formatter every day. It is an incredible pain. Of course the solution is getting rid of printf style formatting, not string_view.
  - o11c 2y ago
    The hardest part of passing `std::string` to `printf` was getting the macro to convince the pre-standard-C++11 compiler that it was `constexpr` enough so that `-Werror=format` would work. I found it was easiest to sometimes allocate a temporary, if the input wasn't known to be NUL-terminated.
- jeffbee 2y ago
  Are you suggesting printf("%.*s", static_cast<int>(sv.size()), sv.data()) ?
  - humanrebar 2y ago
    Well, wrap it up in something more ergonomic, but it works. I'm usually putting strings into some sort of I/O API (like a logger) instead of hardcoding copies to stdout everywhere. https://stackoverflow.com/a/72575650 https://stackoverflow.com/a/72575650
    - jeffbee 2y ago
      Wrap it way up into something ergonomic and idiomatic, like fmt.
      - humanrebar 2y ago
        Sure. I do. But there are tradeoffs even then. Look at the error messages compared to printf for example.
throw4023042q0 2y ago
> This is also one of the reasons why printf won't work. You cannot pass a type like std::string to a variable args function. Can't you just call .c_str() on the std::string first to get to the null-terminated char array? https://cplusplus.com/reference/string/string/c_str/ https://cplusplus.com/reference/string/string/c_str/
AnimalMuppet 2y ago
std::string str; printf("%s\n", str.c_str());
cmovq 2y ago
I can understand banning it. It’s important to understand std::string is more of a string builder implementation, which is rarely what you want, but people treat it as the default way to handle strings in C++. Too often I have to fix code that makes liberal use of std::string, making copies and allocations everywhere for no apparent reason, when string_view or better const char* would do.

hot_gril 2y ago

Was gonna say, this guide is too light on examples. So an example of string usage would be passing around null-terminated char arrays.

humanrebar 2y ago

std::string_view with %.*s as a string formatter work well enough if you're set on using printf.

gpderetta 2y ago
I have to use std::string_view with %.*s as a string formatter every day. It is an incredible pain. Of course the solution is getting rid of printf style formatting, not string_view.
- o11c 2y ago
  The hardest part of passing `std::string` to `printf` was getting the macro to convince the pre-standard-C++11 compiler that it was `constexpr` enough so that `-Werror=format` would work. I found it was easiest to sometimes allocate a temporary, if the input wasn't known to be NUL-terminated.
jeffbee 2y ago
Are you suggesting printf("%.*s", static_cast<int>(sv.size()), sv.data()) ?
- humanrebar 2y ago
  Well, wrap it up in something more ergonomic, but it works. I'm usually putting strings into some sort of I/O API (like a logger) instead of hardcoding copies to stdout everywhere. https://stackoverflow.com/a/72575650 https://stackoverflow.com/a/72575650
  - jeffbee 2y ago
    Wrap it way up into something ergonomic and idiomatic, like fmt.
    - humanrebar 2y ago
      Sure. I do. But there are tradeoffs even then. Look at the error messages compared to printf for example.

throw4023042q0 2y ago

> This is also one of the reasons why printf won't work. You cannot pass a type like std::string to a variable args function. Can't you just call .c_str() on the std::string first to get to the null-terminated char array? https://cplusplus.com/reference/string/string/c_str/ https://cplusplus.com/reference/string/string/c_str/

AnimalMuppet 2y ago

std::string str; printf("%s\n", str.c_str());

cmovq 2y ago

I can understand banning it. It’s important to understand std::string is more of a string builder implementation, which is rarely what you want, but people treat it as the default way to handle strings in C++. Too often I have to fix code that makes liberal use of std::string, making copies and allocations everywhere for no apparent reason, when string_view or better const char* would do.