Scanf沒有工作

Question

在我的代碼中，第二個scanf不工作，無法讀取字符。 我該如何解決這個問題？

#include <stdio.h> 
int main() { 
int a, result; 
// ***************** Menu ******************* 
printf("Hello !!! \n The Operations That This Calculator Can Do :"); 
printf("\n1. Simple Operations"); 
printf("\n2. Calculate The Biggest Number"); 
printf("\n3. Taylor expansion"); 
printf("\n4. Sum Digits Of a Number"); 
printf("\n5. Found The Prime Numbers Before The Number That You Entered"); 
printf("\nEnter The Number Of Operation That You Want : "); 
scanf_s("%d", &a); 
if (a == 1){ 
    char ch; 
    int num1, num2; 
    printf("\n Please Enter Your Operation Like That (- 5 3) : "); 
    scanf_s("%c", &ch); 
    if (ch == '-'){ scanf_s("%d", &num1); scanf_s("%d", &num2); result = num1 - num2; printf("\n > %d", result); } 
    if (ch == '+'){ scanf_s("%d", &num1); scanf_s("%d", &num2); result = num1 + num2; printf("\n > %d", result); } } return 0; } 

Answer 1

試試這個：我改變scanf_s（）以scanf函數，給空間％C爲％C轉換符不會自動跳過任何前導空格，所以如果有輸入流中的寄生換行符（從例如，以前的條目），scanf調用將立即消耗它。

#include <stdio.h> 
int main() { 
int a, result; 
// ***************** Menu ******************* 
printf("Hello !!! \n The Operations That This Calculator Can Do :"); 
printf("\n1. Simple Operations"); 
printf("\n2. Calculate The Biggest Number"); 
printf("\n3. Taylor expansion"); 
printf("\n4. Sum Digits Of a Number"); 
printf("\n5. Found The Prime Numbers Before The Number That You Entered"); 
printf("\nEnter The Number Of Operation That You Want : "); 
scanf("%d", &a); 
if (a == 1){ 
char ch; 
int num1, num2; 
printf("\n Please Enter Your Operation Like That (- 5 3) : "); 
scanf(" %c", &ch); 
if (ch == '-'){ scanf(" %d", &num1); scanf(" %d", &num2); result = num1 - 
num2; printf("\n > %d", result); } 
if (ch == '+'){ scanf(" %d", &num1); scanf(" %d", &num2); result = num1 + 
num2; printf("\n > %d", result); } } 
system("pause"); }