/* #include<stdio.h> int is_prime(int n) { for(int i = 2; i <= n/2; i ++) if(n % 2 == 0) return 0; return 1; } int main() { int n; printf("Enter a number(exit when n<=1):"); scanf("%d", &n); if(is_prime(n) && n > 1) printf("%d is a prime number", n); else if(n > 1) printf("%d is not a prime number", n); else ; return 0; } #include<stdio.h> int is_prime(int n) { for(int i = 2; i <= n/2; i ++) if(n % 2 == 0) return 0; return 1; } int main() { int n; printf("Enter a even number(n>=6):"); scanf("%d", &n); if(n < 6 || n%2 != 0) printf("error: illegal input "); else for(int i = 2; i <= n/2; i ++) if(is_prime(i) && is_prime(n-i)) printf("%d = %d + %d ", n, i, n-i); return 0; } #include<stdio.h> int fac(int x) { if(x == 1) return 1; else return x*fac(x-1); } int main() { int n, m; int result; printf("Enter the value of n and m:"); scanf("%d %d", &n, &m); result = fac(n)/(fac(n-m)*fac(m)); printf("Result is %d ", result); return 0; } #include<stdio.h> void selectMaxAndMin(int A[][4], int row, int c) //int A[][]: array type has incomplete element type ? { int max, min; max = min = A[0][0]; for(int i = 0; i < row; i ++) for(int j = 0; j < c; j ++){ if(A[i][j] > max) max = A[i][j]; if(A[i][j] < min) min = A[i][j]; } printf("max = %d, min = %d ", max, min); } void main() { int A[4][4] = {1, 5, 3, 6, 2, 4, 5, 7, 3, 9, 8, 0, 4, 1, 9, 5}; selectMaxAndMin(A, 4, 4); } #include<stdio.h> char trans(char c) { if(c >= 'a' && c <= 'z' || c >= 'A' && c <= 'Z') return c+4; else return c; } void main() { char s[100]; char c; int i; i = 0; while((c = getchar()) != ' ') s[i++] = trans(c); s[i] = ' '; printf("%s ", s); } #include<stdio.h> #define ROW 2 #define COL 3 void trans(int arr[100][100]) //int arr[][100] 无法正常传值???? { int k = 0; printf("transArr: "); for(int i = 0; i <= COL; i ++){ for(int j = 0; j <= ROW; j ++) printf("%5d", arr[j][i]); printf(" "); } } void main() { int oriArr[100][100]; printf("Enter the value of oreArr: "); for(int i = 0; i <= ROW; i ++) for(int j = 0; j <= COL; j ++){ printf("oriArr[%d][%d]=", i, j); scanf("%d", &oriArr[i][j]); } printf("oriArr: "); for(int i = 0; i <= ROW; i ++){ for(int j = 0; j <= COL; j ++) printf("%5d", oriArr[i][j]); printf(" "); } trans(oriArr); } #include<stdio.h> char s[100]; void My_char(int i) { if(i == 0) printf("%c", s[0]); else{ printf("%c", s[i]); My_char(i-1); } } int main() { char c; int i; i = 0; printf("Enter a String: "); while((c = getchar()) != ' ') s[i++] = c; printf("After be reverse: "); My_char(i-1); } */