39 lines
1.3 KiB
C++
39 lines
1.3 KiB
C++
#include <string>
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// ...
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// empty string declaration
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std::string str; // (default constructed)
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std::string str(); // (default constructor, no parameters)
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std::string str{}; // (default initialized)
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std::string str(""); // (const char[] conversion)
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std::string str{""}; // (const char[] initializer list)
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if (str.empty()) { ... } // to test if string is empty
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// we could also use the following
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if (str.length() == 0) { ... }
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if (str == "") { ... }
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// make a std::string empty
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str.clear(); // (builtin clear function)
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str = ""; // replace contents with empty string
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str = {}; // swap contents with temp string (empty),then destruct temp
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// swap with empty string
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std::string tmp{}; // temp empty string
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str.swap(tmp); // (builtin swap function)
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std::swap(str, tmp); // swap contents with tmp
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// create an array of empty strings
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std::string s_array[100]; // 100 initialized to "" (fixed size)
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std::array<std::string, 100> arr; // 100 initialized to "" (fixed size)
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std::vector<std::string>(100,""); // 100 initialized to "" (variable size, 100 starting size)
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// create empty string as default parameter
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void func( std::string& s = {} ); // {} generated default std:string instance
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