For loops for循环
For loops in C are straightforward(简单的). They supply（提供） the ability to create a loop - a code block that runs multiple times（多次）. For loops require an iterator variable（迭代变量）, usually notated（标记） as i.
For loops give the following functionality(功能):
-
Initialize(初始化) the iterator variable using an initial value
-
Check if（是否） the iterator has reached（达到） its final value
-
Increases the iterator
For example, if we wish to iterate on a block for 10 times, we write:
int i;
for (i = 0; i < 10; i++) {printf("%d\n", i);
}
This block will print the numbers 0 through 9 (10 numbers in total 总共).
For loops can iterate（迭代） on array values. For example, if we would want to sum all the values of an array, we would use the iterator i as the array index:
int array[10] = { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 };
int sum = 0;
int i;for (i = 0; i < 10; i++) {sum += array[i];
}/* sum now contains a[0] + a[1] + ... + a[9] */
printf("Sum of the array is %d\n", sum);
Exercise
Calculate（计算 ）the factorial 阶乘 (multiplication of all items array[0] to array[9], inclusive), of the variable array.
原：
#include <stdio.h>int main() {int array[] = { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 };int factorial = 1;int i;/* calculate the factorial using a for loop here*/printf("10! is %d.\n", factorial);
}
改：
#include <stdio.h>int main() {int array[] = { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 };int factorial = 1;int i;/* calculate the factorial using a for loop here*/for(i = 0; i<10;i++){factorial *=array[i];}printf("10! is %d.\n", factorial);
}
