在指向整数数组的指针中使用scanf

该程序应该存储3个学生的输入成绩并打印平均值。 但是，如果我要求学生B的平均分，它会打印出学生A的平均分数，而学生A的平均分数为0.我似乎无法找到我出错的地方..请帮助例如Student_A = {7,7， 7}，Student_B = {8,8,8}; ave（学生_B）= 7

#include int i; char j; int student_A[4]; int student_B[4]; int student_C[4]; float grade_input(int student[]); float ave(int student[]); main(){ printf("For Student A:\n"); grade_input(&student_A[4]); printf("For Student B:\n"); grade_input(&student_B[4]); printf("For Student C:\n"); grade_input(&student_C[4]); do{ printf("Whose average grade do you want to see, a ,b ,c? "); getchar(); scanf("%c", &j); if(j=='a'){ printf("%.2f\n", ave(student_A)); } if(j=='b'){ printf("%.2f\n", ave(student_B)); } if(j=='c'){ printf("%.2f\n", ave(student_C)); } }while(j=='a' || j=='b' || j=='c'); } float grade_input(int student[]){ int i; for(i=0; i<3; i++){ printf("Enter grade %d: ", i+1); scanf("%d", &student[i]); } } float ave(int student[]){ return (student[0] + student[1] + student[2])/3.0; } 

Answer 1

你遇到的问题是将&student_X[4]传递给grade_input() 。 这只是非法的，因为它是一个4元素arrays; 没有定义访问带有下标4的元素。 由于它们是连续定义的，当你用&student_A[4]调用grade_input()函数时，你最终会有效地将指针发送到student_B ，而这正是你所看到的！

您应该将指针传递给数组。 我稍微改写了下面的代码来说明。

 #include int i; char j; int student_A[4]; /* ******* */ /* note that student_A is defined as a 4 element array */ int student_B[4]; int student_C[4]; float grade_input(int student[]); float ave(int student[]); main(){ printf("For Student A:\n"); /* ******* */ /* note that student_A is defined as a 4 element array */ /* a pointer to the array is just student_A, not &student_A[4] */ grade_input(student_A); printf("For Student B:\n"); grade_input(student_B); printf("For Student C:\n"); grade_input(student_C); do{ printf("Whose average grade do you want to see, a ,b ,c? "); scanf("%c", &j); if(j=='a'){ printf("%.2f\n", ave(student_A)); } else if(j=='b'){ printf("%.2f\n", ave(student_B)); } else if(j=='c'){ printf("%.2f\n", ave(student_C)); } else printf ( "Enter a, b or c\n" ); }while(j != 'q'); } float grade_input(int student[]){ int i; for(i=0; i<3; i++){ printf("Enter grade %d: ", i+1); scanf("%d", &student[i]); } } float ave(int student[]){ return (student[0] + student[1] + student[2])/3.0; } 

Answer 2

没有必要做getchar(); 在scanf("%c", &j);之前scanf("%c", &j); 你应该用fflush(stdout);清理缓冲区的人fflush(stdout); 或者做

 char c; while ((c = getchar()) != '\n'); 

所以你的完整代码应该像：

 #include int i; char j; int student_A[4]; int student_B[4]; int student_C[4]; float grade_input(int student[]); float ave(int student[]); main(){ printf("For Student A:\n"); grade_input(&student_A[4]); printf("For Student B:\n"); grade_input(&student_B[4]); printf("For Student C:\n"); grade_input(&student_C[4]); do{ printf("Whose average grade do you want to see, a ,b ,c? "); fflush(stdout); // THE CHANGE scanf("%c", &j); if(j=='a'){ printf("%.2f\n", ave(student_A)); } if(j=='b'){ printf("%.2f\n", ave(student_B)); } if(j=='c'){ printf("%.2f\n", ave(student_C)); } }while(j=='a' || j=='b' || j=='c'); } float grade_input(int student[]){ int i; for(i=0; i<3; i++){ printf("Enter grade %d: ", i+1); scanf("%d", &student[i]); } } float ave(int student[]){ return (student[0] + student[1] + student[2])/3.0; }