收到錯誤「預期標識符或‘（’前‘{’令牌用C

Question

任何幫助將是巨大的！

#include <stdio.h> 
#define pi 3.14159 



int main() 
{ 
    float r; 
    char PI; 

/*Program for circumference. */ 

    printf(" This is a program that will calculate circumference.\n"); 
    printf("Please put in your radius.\n"); 

    scanf("%f", &r); 
    printf("Please input PI\n"); 
    PI = getchar(); 
} 

    { 
    if {(char != PI || 3.14); 
    printf("Incorect value\n"); 
} 

    else { 
    printf("Thank you, the circumference is now.\n"); 
    printf("%f", (r) * pi *2); 
} 


return 0; 

} 

我試圖找出這個錯誤，我肯定，四處搜尋，但真的沒什麼彈起我的具體問題，如果有幫助，這是正確的「if」語句開始之前，也許我可以用一個太多的「{」？

Answer 1

我已經指出了它comments.Make使用帽習慣的錯誤爲#define宏，不是爲了variables.And最後，您if的條件應該是if(PI!=pi)卸下襬臂的{之間和(，並且還之後;的)

#include <stdio.h> 
#define pi 3.14159 



int main() 
{ 
    float r; 
    char PI; 

/*Program for circumference. */ 

    printf(" This is a program that will calculate circumference.\n"); 
    printf("Please put in your radius.\n"); 

    scanf("%f", &r); 
    printf("Please input PI\n"); 
    PI = getchar(); 
} //This is the source of error as `main()` ends after this `}' 

    { 
    if(PI!=pi) //You have used a `;` after if's condition & an extra '{' before it 
    printf("Incorect value\n"); 
} 

    else { 
    printf("Thank you, the circumference is now.\n"); 
    printf("%f", (r) * pi *2); 
} 


return 0; 

} 

Answer 2

您在第一}終止您的主要功能你有一個不平衡的開放和關閉大括號的匹配，這是造成這個問題，你也有一個與你的if聲明有關的問題

if {(char != PI || 3.14); 

應爲

if (char != PI || 3.14) 

或者更具體地說是整個的if-else應該

if (char != PI || 3.14) 
{ 
    printf("Incorect value\n"); 
} else { 
    printf("Thank you, the circumference is now.\n"); 
    printf("%f", (r) * pi *2); 
}