c语言数组中添加一个数(c语言数组知识点总结)

Introduction: C array basics

Arrays in C are a fundamental feature of the language. They allow us to store multiple values of the same type in a single variable. This makes them very useful for a variety of programming tasks. Arrays in C are static, which means that their size must be declared at the time of creation and cannot be changed during runtime. In this article, we will discuss how to add an element to an array in C.

Method 1: Expanding the array

The simplest way to add an element to an array is to expand the array by one element and insert the new value. This method works well if you know the maximum size of your array and the number of elements you need to store is small. Here's how you can do it:

int arr[5] = {1, 2, 3, 4, 5};
int new_element = 6;
int size = sizeof(arr)/sizeof(arr[0]);

int new_arr[size+1];

for (int i = 0; i < size; i++)
{
    new_arr[i] = arr[i];
}

new_arr[size] = new_element;

// the contents of new_arr are {1, 2, 3, 4, 5, 6}

In this method, we create a new array called new_arr that has a size one larger than the original array. We then iterate over the original array, copying its elements into the new array. Finally, we insert the new element into the last element of the new array.

Method 2: Using dynamic memory allocation

If you don't know the maximum size of your array or you need to store a large number of elements, you can use dynamic memory allocation to create an array with a size that can be determined at runtime. Here's how:

// allocate memory for the original array
int *arr = (int *) malloc(sizeof(int)*5);

// fill the array with values
for (int i = 0; i < 5; i++)
{
    arr[i] = i+1;
}

// add a new element to the array
arr = (int *) realloc(arr, sizeof(int)*6);
arr[5] = 6;

// the contents of arr are {1, 2, 3, 4, 5, 6}

In this method, we first allocate memory for the original array using the malloc function. We then fill the array with values. To add a new element to the array, we use the realloc function to resize the array to a new size and copy its contents into the new memory location. We then insert the new element into the last element of the array.

Conclusion

Adding an element to an array in C can be accomplished in a variety of ways, depending on the size and requirements of your array. Using the methods outlined above will allow you to add a new element to your array and continue to use it in your program.