结构

for(初始化表达式;条件表达式;循环后的操作表达式) {
    循环体;
}

1.求出1-10之间数据之和:

class Hello2 {
    public static void main(String[] args) {
        int sum = 0;
        for (int i = 1;i <= 10 ;i++ )
        {
            sum = i + sum;
        }
         System.out.println(sum);
            
    }
}

结果:

  2.求出1-100之间偶数和:

public static void main(String[] args) {
        int sum = 0;
        for (int i = 1;i <= 100 ;i++ )
        {
            if (i % 2 == 0)
            {
                sum = i + sum;
            }
        }
         System.out.println(sum);
            
    }
}

结果:

 

3.求出1-100之间奇数和:

方法一:

public static void main(String[] args) {
        int sum = 0;
        for (int i = 1;i <= 100 ;i++ )
        {
            if (i % 2 == 1)
            {
                sum = i + sum;
            }
        }
         System.out.println(sum);
            
    }
}

方法二:

class Hello2 {
    public static void main(String[] args) {
        int sum = 0;
        for (int i = 1;i <= 100 ;i+=2 )
        {
                sum = i + sum;
        }
         System.out.println(sum);
            
    }
}

 

结果: