Can the elements in an array be of different data types?

No; the data type of each element in the array is the same. Array is a commonly used data structure, which is a collection of ordered data; each element in the array has the same data type, and a unified array name and subscript can be used to uniquely identify the elements in the array.

The operating environment of this tutorial: Windows 7 system, version c99, Dell G3 computer.

No; the data types of each element in the array are the same.

The concept and definition of array

We know that in order to put data into memory, memory space must be allocated first. To put in 4 integers, you have to allocate 4 int type memory spaces:

int a[4];

In this way, 4 int type memory spaces are allocated in the memory, a total of 4×4=16 bytes, And gave them a name, called a.

We call such a set of data an array (Array), each data it contains is called an array element (Element), and the number of data contained is called the array length (Length) , for example, int a[4]; defines an integer array with a length of 4, and the name is a.

Each element in the array has a serial number. This serial number starts from 0, not from the familiar 1, and is called an index. When using array elements, just specify the subscript, in the form:

arrayName[index]

arrayName is the name of the array, and index is the subscript. For example, a[0] represents the 0th element, and a[3] represents the 3rd element.

Next we put the 4 integers in the first line into the array:

a[0]=20;
a[1]=345;
a[2]=700;
a[3]=22;

The 0, 1, 2, and 3 here are the array subscripts, a[0], a[ 1], a[2], a[3] are array elements.

During the learning process, we often use loop structures to put data into arrays (that is, assign values ​​to array elements one by one), and then use loop structures to output (that is, read the values ​​of array elements in sequence) , let's demonstrate how to put the ten numbers 1~10 into the array:

#include <stdio.h>
int main(){
    int nums[10];
    int i;
   
    //将1~10放入数组中
    for(i=0; i<10; i++){
        nums[i] = (i+1);
    }
   
    //依次输出数组元素
    for(i=0; i<10; i++){
        printf("%d ", nums[i]);
    }
   
    return 0;
}

Running result:

1 2 3 4 5 6 7 8 9 10

The variable i is both the array subscript and the loop condition; The array subscript serves as the loop condition, and the loop ends when the last element is reached. The maximum subscript of the array nums is 9, which means it cannot exceed 10, so we stipulate that the condition of the loop is i<10. Once i reaches 10, the loop must end.

Change the above code to allow the user to enter 10 numbers and put them into the array:

#include <stdio.h>
int main(){
    int nums[10];
    int i;
   
    //从控制台读取用户输入
    for(i=0; i<10; i++){
        scanf("%d", &nums[i]);  //注意取地址符 &，不要遗忘哦
    }
   
    //依次输出数组元素
    for(i=0; i<10; i++){
        printf("%d ", nums[i]);
    }
   
    return 0;
}

Running results:

22 18 928 5 4 82 30 10 666 888↙
22 18 928 5 4 82 30 10 666 888

In the 8th line of code, scanf() reads When fetching data, an address is required (the address is used to indicate the storage location of the data), and nums[i] represents a specific array element, so we need to add & in front to get the address.

Finally, let’s summarize how the array is defined:

dataType  arrayName[length];

dataType is the data type, arrayName is the array name, and length is the array length. For example:

float m[12];  //定义一个长度为 12 的浮点型数组
char ch[9];  //定义一个长度为 9 的字符型数组

It should be noted that:

1) The data type of each element in the array must be the same, for int a[4];, each element Both must be int.

2) The length of the array is preferably an integer or a constant expression, such as 10, 20*4, etc., so that it can run under all compilers; if length contains variables, such as n, 4 *m etc., an error will be reported under some compilers. We will discuss this specifically in the section "Variable length arrays in C language: using variables to specify the length of the array".

3) When accessing array elements, the value range of the subscript is 0 ≤ index < length. If it is too large or too small, it will cross the boundary, causing the array to overflow and unpredictable situations. We will discuss this in "C Language" The section "Array Out-of-Bounds and Overflow" focuses on the discussion. Please pay attention to it.

For more programming-related knowledge, please visit: Introduction to Programming! !

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