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Fix CI errors due to missing whitespace around operators (#1037)

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Also rephrase comments to avoid overlong lines.
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Jonathan Wakely 2017-10-02 19:39:18 +01:00 committed by GitHub
parent 2184c57dd1
commit 6153d69b2c
1 changed files with 13 additions and 11 deletions
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CppCoreGuidelines.md
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@ -11167,12 +11167,13 @@ Helps make style consistent and conventional.
By definition, a condition in an `if`-statement, `while`-statement, or a `for`-statement selects between `true` and `false`.
A numeric value is compared to `0` and a pointer value to `nullptr`.
if (p) { ... } // means "if `p` is not `nullptr`, good
if (p!=0) { ... } // means "if `p` is not `nullptr`, redundant `!=0`; bad: don't use 0 for pointers
if (p!=nullptr) { ... } // means "if `p` is not `nullptr`, redundant `!=nullptr`, not recommended
// These all mean "if `p` is not `nullptr`"
if (p) { ... } // good
if (p != 0) { ... } // redundant `!=0`; bad: don't use 0 for pointers
if (p != nullptr) { ... } // redundant `!=nullptr`, not recommended
Often, `if (p)` is read as "if `p` is valid" which is a direct expression of the programmers intent,
whereas `if (p!=nullptr)` would be a long-winded workaround.
whereas `if (p != nullptr)` would be a long-winded workaround.
##### Example
@ -11180,14 +11181,14 @@ This rule is especially useful when a declaration is used as a condition
if (auto pc = dynamic_cast<Circle>(ps)) { ... } // execute is ps points to a kind of Circle, good
if (auto pc = dynamic_cast<Circle>(ps); pc!=nullptr) { ... } // not recommended
if (auto pc = dynamic_cast<Circle>(ps); pc != nullptr) { ... } // not recommended
##### Example
Note that implicit conversions to bool are applied in conditions.
For example:
for (string s; cin>>s; ) v.push_back(s);
for (string s; cin >> s; ) v.push_back(s);
This invokes `istream`'s `operator bool()`.
@ -11195,13 +11196,13 @@ This invokes `istream`'s `operator bool()`.
It has been noted that
if(strcmp(p1,p2)) { ... } // are the two C-style strings equal? (mistake!)
if(strcmp(p1, p2)) { ... } // are the two C-style strings equal? (mistake!)
is a common beginners error.
If you use C-style strings, you must know the `<cstring>` functions well.
Being verbose and writing
if(strcmp(p1,p2)!=0) { ... } // are the two C-style strings equal? (mistake!)
if(strcmp(p1, p2) != 0) { ... } // are the two C-style strings equal? (mistake!)
would not save you.
@ -11209,9 +11210,10 @@ would not save you.
The opposite condition is most easily expressed using a negation:
if (!p) { ... } // means "if `p` is`nullptr`, good
if (p==0) { ... } // means "if `p` is `nullptr`, redundant `!=0`; bad: don't use `0` for pointers
if (p==nullptr) { ... } // means "if `p` is `nullptr`, redundant `==nullptr`, not recommended
// These all mean "if `p` is `nullptr`"
if (!p) { ... } // good
if (p == 0) { ... } // redundant `!= 0`; bad: don't use `0` for pointers
if (p == nullptr) { ... } // redundant `== nullptr`, not recommended
##### Enforcement