这篇understanding-lvalues-and-rvalues-in-c-and-c比较清晰的介绍了,左值右值的关系以及c++11 move的语义的实现原理。 视频资源 Scott Meyers--speech 小结
C/C++ 关于l-value跟r-value 一般来说,以“=” 作为分界,左边的叫左值(l-value),右边的叫右值(r-value)。 虽然通俗,不过这种说法,我是认为是不妥的。 今天有人问了条面试题, a=++b++; 这式子编译无法通过,error: non-lvalue in increment 错误信息翻译过来就是:自增无左值 下面来分析错误, 首先,我...
This terminology, “lvalues” and “rvalues”, is talking about the same thing. The terminology derives from whether the value can/must be on theleftorrightof an assignment. In the BNF for C, we might write: assignment_expr::=lvalue"="(lvalue|rvalue); lvalue::=var|dereference|array_loo...
Some examples of correct and incorrect usages are: Copy // lValues_rValues.cpp int main() { int i, j, *p; i = 7; // OK variable name is an l-value. 7 = i; // C2106 constant is an r-value. j * 4 = 7; // C2106 expression j * 4 yields an r-value. *p = i; //...
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所以拉文克劳的智慧可能被曲解了一些,它不一定意味着“学习好”,相反它更多指的是热爱思辨、兴趣至上,对某一领域有极强的探索精神,不热衷社交,不贪图名利,不爱麻烦别人也讨厌被麻烦,容易钻牛角尖,容易执迷。 拉文克劳的智慧服从于本人的追求。 这个智慧不等同于聪明。
In both C and C++, certain operators require lvalues for some of their operands. The table below lists these operators and additional constraints on their usage. For example, all assignment operators evaluate their right operand and assign that value to their left operand. The left operand must...
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An l-value expression in parentheses Aconstobject (a nonmodifiable l-value) The term "r-value" is sometimes used to describe the value of an expression and to distinguish it from an l-value. All l-values are r-values but not all r-values are l-values. ...