Question

#include <set>
#include <string>
using namespace std;
struct StudInfo{                    //declaration of structure
    string name;
    int id;
};
int compareID(StudInfo a , StudInfo b){          //Compare function as a parameter 
    if(a.id == b.id) return 0;                   //that is being passed to the set s
    if(a.id < b.id) return -1;
    else return 1;
}
int main(){
    set<StudInfo> s(CompareID);
    return 0;

}

在main（）范围内我收到此错误（错误C2065：'CompareID'：未声明的标识符）虽然相同的代码已成功编译在编写此代码的视频讲座中请帮助。

Answer 1

编程的黄金法则：99.9％的编译器错误是由于你，不是编译器。

尽管在视频讲座中成功编译了相同的代码其中编写此代码

不，没有！

我怎么知道？嗯，这很简单。首先，我忽略了编译器出错的任何可能性。然后，我可以专注于源代码，和编译器输出。

解决方案很简单：将init: ## _Command call():_ init: _method start:_ getOrInitGit init: _ looking for git folder in /home/work/projects/my-application _ init: _ found existing git folder _ : _method END:_ GitHelper: _method start:_ remoteBranchExists GitHelper: _ checking for branch: master _ GitHelper: _ got 29 remote refs _ GitHelper: _ ref name: refs/remotes/origin/1.0.x _ GitHelper: _ ref simple name: 1.0.x _ GitHelper: _ simple name equals branch? false _ GitHelper: _ ref name: refs/remotes/origin/1.1.x _ GitHelper: _ ref simple name: 1.1.x _ GitHelper: _ simple name equals branch? false _ GitHelper: _ ref name: refs/remotes/origin/1.2.x _ GitHelper: _ ref simple name: 1.2.x _ GitHelper: _ simple name equals branch? false _ GitHelper: _ ref name: refs/remotes/origin/master _ GitHelper: _ ref simple name: master _ GitHelper: _ simple name equals branch? true _ : _method END:_ GitHelper: _method start:_ remoteBranchExists GitHelper: _ checking for branch: develop _ GitHelper: _ got 29 remote refs _ GitHelper: _ ref name: refs/remotes/origin/1.0.x _ GitHelper: _ ref simple name: 1.0.x _ GitHelper: _ simple name equals branch? false _ GitHelper: _ ref name: refs/remotes/origin/1.1.x _ GitHelper: _ ref simple name: 1.1.x _ GitHelper: _ simple name equals branch? true _ : _method END:_ # JGitFlow Log - Wed Oct 05 2016 12:25:34 IST ## Configuration JGit Version: 3.0.0.201306101825-r JGitFlow Version: 0.21 Master name: master Origin master exists = true Develop name: develop Origin develop exists = true feature name: feature/ release name: release/ hotfix name: hotfix/ support name: support/ versiontag name: -------------------------------------------------------------------------------- DefaultFlowFeatureManager: _ # Maven JGitFlow Plugin _ DefaultFlowFeatureManager: _ _ DefaultFlowFeatureManager: _ ## Configuration _ DefaultFlowFeatureManager: _ _ DefaultFlowFeatureManager: _ Maven Version: 3.3.9 _ DefaultFlowFeatureManager: _ _ DefaultFlowFeatureManager: _ Maven JGitFlow Plugin Version: 1.0 _ DefaultFlowFeatureManager: _ _ DefaultFlowFeatureManager: _ args: _ DefaultFlowFeatureManager: _ base dir: /home/work/project/myapplication _ DefaultFlowFeatureManager: _ default development version: null _ DefaultFlowFeatureManager: _ default feature name: null _ DefaultFlowFeatureManager: _ default release version: null _ DefaultFlowFeatureManager: _ release branch version suffix: release _ DefaultFlowFeatureManager: _ tag message: tagging release ${version} _ DefaultFlowFeatureManager: _ allow snapshots: false _ DefaultFlowFeatureManager: _ auto version submodules: false _ DefaultFlowFeatureManager: _ enable feature versions: true _ DefaultFlowFeatureManager: _ enable ssh agent: true _ DefaultFlowFeatureManager: _ feature rebase: false _ DefaultFlowFeatureManager: _ interactive: true _ DefaultFlowFeatureManager: _ keep branch: false _ DefaultFlowFeatureManager: _ no build: false _ DefaultFlowFeatureManager: _ no deploy: false _ DefaultFlowFeatureManager: _ no tag: false _ DefaultFlowFeatureManager: _ pushFeatures: true _ DefaultFlowFeatureManager: _ pushReleases: false _ DefaultFlowFeatureManager: _ pushHotfixes: false _ DefaultFlowFeatureManager: _ squash: false _ DefaultFlowFeatureManager: _ update dependencies: true _ DefaultFlowFeatureManager: _ use release profile: true _ DefaultFlowFeatureManager: _ -------------------------------------------------------------------------------- _ DefaultProjectHelper: _ installing ssh console credentials provider _ DefaultProjectHelper: _ installing ssh-agent credentials provider _替换为set<StudInfo> s(CompareID);。仔细注意这个案例。

完成编译工作。

然后我们可以继续您的运行时行为。您的比较器功能未正确指定;你需要用

替换这个功能

set<StudInfo> s(compareID);

对于bool compareID(const StudInfo& a, const StudInfo& b){ return a.id < b.id; } 小于false的所有情况，比较器必须返回a.id。注意我通过b.id引用传递参数以避免不必要的字符串副本。

设置声明C ++时出错

1 个答案: