#include <stdio.h>
int main()
{
    int a=5,b=7,c=100,d,e,f;
    d=a/b*c;
    e=a*c/b;
    f=c/b*a;
    printf("d=%d,e=%d,f=%d\n",d,e,f);
    return 0;
    
}

a乘b除以c，a乘c除以b，c除以b乘a

運算的先後順序不同

#include <stdio.h>
int main() {
int x=1234;
float f=123.456;
double m=123.456;
char ch='a';
char a[]="
 
Hello, world!";
int y=3, z=4;
printf("%d %d\n", y, z);
printf("y=%d, z=%d\n", y,z);
printf("%8d,%2d\n", x,x);
printf("%f, %8f, %8.1f, %0.2f, %.2e\n",f,f,f,f,f);
printf("%lf\n",m);
printf("%3c\n", ch);
printf("%s\n%15s\n%10.5s\n%2.5s\n%.3s\n",a,a,a,a,a);
return 0;
}

#include <stdio.h>
int main() {
 
double x,y;
char c1,c2,c3;
int a1,a2,a3;
    scanf("%d%d%d",&a1,&a2,&a3);
    printf("%d,%d,%d\n",a1,a2,a3);
    scanf("%c%c%c",&c1,&c2,&c3);
    printf("%c%c%c\n",c1,c2,c3);
    scanf("%lf,%lf",&x,&y);
    printf("%.1f,%.1lf\n",x,y);
return 0;
}

#include <stdio.h>
int
 
 main() {
    char x;

    x = getchar();
    
    if(x<='9'&&x>='0')
        printf("%c是數字字元\n", x);
    else if(x<='z'&&x>='a'||x>='A'&&x<='Z')  
        printf("%c是英文字母\n", x);
    else
        printf("%c是其它字元\n", x);
    
    
    return 0;
} 

#include <stdio.h>
int main() {
    char ans1, ans2;
    printf("複習了沒? (輸入y或Y表示複習了，輸入n或N表示沒複習) :  ");
    ans1 = getchar();
    
    getchar();
    
    printf("\n動手敲程式碼了沒? (輸入y或Y表示敲了，輸入n或N表示木有敲) :  ");
    ans2 = getchar();
    
    if(ans1=='Y'&&ans2=='Y'||ans1=='y'&&ans2=='y'||ans1=='Y'&&ans2=='y'||ans1=='y'&&ans2=='Y')
        printf("\n羅馬不是一天建成的:)\n");    
    else
        printf("\n羅馬不是一天毀滅的。。。\n");

    return 0;
} 

#include <stdio.h>
int main(){
    int n,sum;
    int i = 1;
    int p = 1;
    scanf("%d",&n);
    while(i<=n){
    
    p = p*2;
    i++;
}
    sum = 1*(1-p)/(1-2);
    printf("n = %d時,sum = %d",n,sum);
    return 0;    
    
}