C++ 错误：字符串在C中获得意外输出

/*write a program to insert a string into main string*/
#include <stdio.h>

int main()
{
    char text[100], str[20], ins_text[100];
    int i = 0, j = 0, k = 0, pos;
    printf("enter main text: ");
    gets(text);
    printf("enter string to be inserted: ");
    gets(str);
    printf("enter the position to be inserted: ");
    scanf("%d", &pos);

    while (text[i] != '\0')
    {
        if (i == pos)
        {
            while (str[k] != '\0')
            {
                ins_text[j] = str[k];
                j++;
                k++;
            }
        }
        else
        {
            ins_text[j] = text[i];
            j++;
        }
        i++;
    }

    ins_text[j] = '\0';
    printf("\n the new string is: ");
    puts(ins_text);
    return 0;
}

在航站楼

$ ./a.exe

enter main text: newsman
enter string to be inserted: paper
enter the position to be inserted: 4

The new string is: `newspaperan`

在上面的最终输出中:-"新字符串是:Newspperan"，字母"m"缺失. 我认为这是因为在While循环中增加了"j++"； 有什么办法修好它吗？