C++STL函数之count函数与count_if函数

- 日理万妓 2022-02-24 05:22 258阅读 0赞

count函数就是统计数组中有多少个数与要查询的数相同

代码实例：

/*
    
    */
    #include<map>
    #include<set>
    #include <vector>
    #include<stack>
    #include<queue>
    #include<cmath>
    #include<string>
    #include<cstdio>
    #include<cstring>
    #include<cstdlib>
    #include<iostream>
    #include<algorithm>
    using namespace std;
    #define ll unsigned long long
    #define inf 0x3f3f3f
    #define esp 1e-8
    #define bug {printf("mmp\n");}
    #define mm(a,b) memset(a,b,sizeof(a))
    #define T() int test,q=1;scanf("%d",&test); while(test--)
    const int maxn=1e4+10;
    const double pi=acos(-1.0);
    const int N=201;
    const int mod=1e9+7;
    int b[]={2,3,6,9,11,11,11,22,32,78};
    int main()
    {
        int a;
        cin>>a;
        int ans=count(b,b+8,a);
        cout<<ans<<endl;
        return 0;
    }

![20190403103331908.png][]

count\_if函数是统计满足条件的计数

代码及实例：

/*
    
    */
    #include<map>
    #include<set>
    #include <vector>
    #include<stack>
    #include<queue>
    #include<cmath>
    #include<string>
    #include<cstdio>
    #include<cstring>
    #include<cstdlib>
    #include<iostream>
    #include<algorithm>
    using namespace std;
    #define ll unsigned long long
    #define inf 0x3f3f3f
    #define esp 1e-8
    #define bug {printf("mmp\n");}
    #define mm(a,b) memset(a,b,sizeof(a))
    #define T() int test,q=1;scanf("%d",&test); while(test--)
    const int maxn=1e4+10;
    const double pi=acos(-1.0);
    const int N=201;
    const int mod=1e9+7;
    int b[]= {2,3,6,9,11,11,11,22,32,78};
    bool cmp(int a)
    {
        return a>10;
    }
    int main()
    {
        int ans=count_if(b,b+8,cmp);
        cout<<ans<<endl;
        return 0;
    }

这里是统计大于10的数

直接输出![20190403104955794.png][]

[20190403103331908.png]: /images/20220224/d922bcffed4e480ba1b64de22d3535a5.png
[20190403104955794.png]: /images/20220224/b20b316e79064c96b563b3fafa38acd8.png