c++中使用index变量报错：error: ‘int index‘ redeclared as different kind of symbol

青旅半醒 2022-12-20 15:56 82阅读 0赞

报错信息如下：

/judger/run/e9f1df8da21548be9d76e7a59262ca1f/main.cpp:7:5: error: 'int index' redeclared as different kind of symbol
     int index = 0;
         ^
    In file included from /usr/include/c++/5/cstring:42:0,
                     from /usr/include/x86_64-linux-gnu/c++/5/bits/stdc++.h:48,
                     from /judger/run/e9f1df8da21548be9d76e7a59262ca1f/main.cpp:1:
    /usr/include/string.h:477:1: note: previous declaration 'const char* index(const char*, int)'
     index (const char *__s, int __c) __THROW
     ^
    /judger/run/e9f1df8da21548be9d76e7a59262ca1f/main.cpp: In function 'int main()':
    /judger/run/e9f1df8da21548be9d76e7a59262ca1f/main.cpp:19:13: error: 'index1' was not declared in this scope
       cout << A[index1] << endl;
                 ^
    /judger/run/e9f1df8da21548be9d76e7a59262ca1f/main.cpp:20:8: error: no post-increment operator for type
       index++;
            ^
    compilation terminated due to -fmax-errors=3.

代码：

#include<bits/stdc++.h>
    using namespace std;
    #define ll long long
    
    const int maxn = 3e4 + 5;
    ll A[maxn], B[maxn], m, n;
    int index = 0;
    
    int main() { 
    	cin >> n >> m;
    	for(int i = 0; i < n; i++) { 
    		cin >> A[i];
    	}
    	for(int j = 0; j < m; j++) { 
    		cin >> B[j];
    	}
    	for(int k = 0; k < m; k++) { 
    		sort(A, A + B[k]);
    		cout << A[index] << endl;
    		index++;
    	}
    	return 0;
    }

解释：c++的string中有一个函数就叫index，而我使用了万能头文件，包含了这个函数，命名冲突了！！

结论：慎用\#include<bits/stdc++.h>