C语言基础

• • 一、printf
  • 二、scanf
  • 三、 for 实例
  • 四、if 实例
  • 五、数组实例

main()  
{
  int k=10;
  double pi=3.1416, a;

  printf("pi=%-12.6f,n", pi);
  printf("pi=%+12.6f,n", pi);
  printf("k=%d, k=%o, k=%#o,n", k,k,k);


//  printf("Please input k and a: ");
//  scanf("%d,%lf",&k,&a);
//  printf("k=%d,a=%fn",k,a);

}

// printf and scanf

#include 

int main()
{    
	int a, b;
	
	printf("input a and b: ");
	scanf("%d%d", &a, &b); 
    
    printf("a=%d, b=%dn", a, b);
    
    return 0; 
}

求 1+2+3+4+…+100 的总和

# include 
int main(void)
{
    int i;
    int sum = 0;  //sum的英文意思是“总和”
    for (i=1; i<=100; ++i)  //++是自加的意思, ++i相当于i = i + 1
    {
        sum = sum + i;  
    }
    printf("sum = %dn", sum);
    return 0;
}

// Example for the usage of if
#include  
int main()
{ 
  int k;

  printf("Please input k: ");
  scanf("%d", &k);
  if (k>10) printf("Your input is larger than 10n");
  else if (k>0) printf("Your input is positiven");
  else printf("You input a negative numbern");
}

#include  

int main()
{ 
    int a[] = {0,2,4,6,8};
    int * pa = a;    
    
    printf("a[0]=%d, a[1]=%d, a[2]=%dn", a[0], a[1], a[2]); 
    
    *pa = 1; // OK, equivalent to a[0]=1
    *(pa+2) = 5; // OK, equivalent to a[2]=5
    // *(a+2) = 5; // OK
    printf("a[0]=%d, a[1]=%d, a[2]=%dn", a[0], a[1], a[2]);

    *(pa++) = 3; // OK, equivalent to a[0]=3; pa = pa + 1;
    // *pa = 6;
    // *(a++) = 3; // ERROR
    // *(a+1) = 5; // OK
    printf("a[0]=%d, a[1]=%d, a[2]=%dn", a[0], a[1], a[2]);    


	return 0;
}