![](https://cos-cdn.shuashuati.com/pipixue-wap/2020-1230-1107-56/ti_inject-812ce.png)
//求一个3×3矩阵对角线元素之和。 #include
#include
using namespace std; #define N 3 int main() { int a[N][N], suma = 0, sumb = 0; for (int i = 0; i < N; i++) for (int j = 0; j < N; j++) cin >> a[i][j]; for (int i = 0; i < N; i++) { suma = suma + ; //【1】主对角线 sumb = sumb + ; //【2】副对角线 } cout << suma << " " << sumb << endl; }