代码实现：

方法一：快慢指针

int removeElement(int *nums, int numsSize, int val) {
    int slow = 0; 
    for (int fast = 0; fast < numsSize; fast++) {  
        if (val != nums[fast]) { 
            nums[slow++] = nums[fast]; 
        }
    }
    return slow;
}

方法二：遍历

int removeElement(int *nums, int numsSize, int val) {
    for (int i = 0; i < numsSize; i++) {
        if (nums[i] == val) {
            for (int j = i; j < numsSize - 1; j++) {
                nums[j] = nums[j + 1];
            }
            numsSize--;
            i--;
        }
    }
    return numsSize;
}