40 lines
1.2 KiB
Plaintext
40 lines
1.2 KiB
Plaintext
== Why is this an issue?
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In {cpp}20, ``++std::string++`` and ``++std::string_view++`` gain new member functions ``++starts_with++`` and ``++ends_with++`` that compare their argument to the prefix and postfix of the string.
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These two functions introduce a standard, concise, and efficient way of checking the prefix and postfix for strings. The ad-hoc implementations predating {cpp}20 are often less readable, less efficient, and less reliable.
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This rule raises an issue when an ad-hoc implementation checks prefixes or postfixes of a string.
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=== Noncompliant code example
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[source,cpp]
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----
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if (6 <= str.size() && str.substr(0, 6) == "prefix") { // Noncompliant
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std::cout <<str <<" starts with the prefix\n";
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}
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if (6 <= str.size() && std::string_view(str.begin(), str.begin() + 6) == "prefix") { // Noncompliant
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std::cout <<str <<" starts with the prefix\n";
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}
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if (7 <= str.size() && str.substr(str.size() - 7) == "postfix") { // Noncompliant
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std::cout <<str <<" ends with the postfix\n";
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}
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----
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=== Compliant solution
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[source,cpp]
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----
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if (str.starts_with("prefix")) {
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std::cout <<str <<" starts with the prefix\n";
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}
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if (str.ends_with("postfix")) {
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std::cout <<str <<" ends with the postfix\n";
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}
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----
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