如何使用循环和内存集以两种方式初始化数组？

Question

I am trying to answer a question in my C programming book, but I am not sure if my answer is correct.
The book doesn't provide any answers though. I am new to C programming, and any help will be appreciated.
Question:
Assume you have declared an array as follows:

float data[1000];

Show two ways to initialize all elements of the array to 0.
Use a loop and an assignment statement for one method, and the memset () function for the other.

my current code :

#include <stdio.h>

float data[1000]; 

main(){
    int count;
    for (count = 0; count < 1000; count++){
        scanf("%f", &data[count]);
    }
    for (count = 0; count < 1000; count++){
        printf("Array %i: %f\n", count, data[count]);
    }
}

Answer 1

A few points to help you get started:

• You're trying to set all items to 0 . Scanf requires you to input all values. This isn't necessary as you could just set them to 0 with data[count]=0.0f; inside of that for loop.
• memset is a function that will do something similar for you (including the for loop). Have a look at the documentation of memset :

memset

void * memset ( void * ptr, int value, size_t num );

Fill block of memory Sets the first num bytes of the block of memory pointed by ptr to the specified value (interpreted as an unsigned char).

Parameters

• ptr: Pointer to the block of memory to fill.
• value: Value to be set. The value is passed as an int, but the function fills the block of memory using the unsigned char conversion of this value.
• num: Number of bytes to be set to the value. size_t is an unsigned integral type.

You should notice that memset only works with bytes. So you can use it to set a float to 0 , as it consists of 4 bytes that are all 0 , but you cannot set it to 1 for instance. But as notices by other users, this just happens to be so on most hardware.

Answer 2

memset(data,0,sizeof(data));

可用于将数组的所有元素分配为0

Answer 3

Show two ways to initialize all elements of the array to 0. Use a loop and an assignment statement for one method, and the memset () function for the other.

1) Using for loop and assignment statement

for(i = 0; i<1000; i++)
    data[i] = 0.0f;

2) Using memset function

memset(&data,0,sizeof(data));

---

Short and simple way supported by c99 spec

float data[1000] = {0.0f};

declare array like this.

Answer 4

Actually there are at least three methods.:)

// first
float data[1000] = { 0.0f };

// second
size_t i;
for ( i = 0; i < 1000; i++ ) data[i] = 0.0f;

// third
memset( data, '\0', sizeof( data ) );

You can also add one more method in C99

// forth
float data[1000] = { [0] = 0.0f };

In C++ you could use also the following declaration

float data[1000] = {};

or

float data[1000] {};

Answer 5

I don't think there is a need for scanf("%f",&data[count]); instead you can directly assign it with data[count]=0;

and if you use the memset() function you can set value to zero directly to an array memset(data,'0',1000);