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- #include <stdio.h>
- #include <stdlib.h>
- #define INCREMENT 10
- #define INIT_SIZE INCREMENT
- char *get_num(void);
- char *reverse_str(char *str);
- char *add_two_strs(char *str1, char *str2);
- char *append_result(char *result, char ch);
- // 获取用户输入的整数
- char *get_num(void)
- {
- char ch;
- char *num; // 存储整个数据的首地址
- char *last; // 最近一次迭代的起始地址
- int limit = 0; // 每次迭代的限制值
- long times = 1; // 记录重新申请多少次内存
- num = (char *)malloc(INIT_SIZE);
- if (num == NULL)
- {
- exit(1);
- }
- last = num;
- printf("请输入一个整数:");
- while ((ch=getchar()) != '\n')
- {
- last[limit++] = ch;
- if (limit >= INCREMENT)
- {
- num = (char *)realloc(num, INIT_SIZE + INCREMENT * times++);
- last += INCREMENT;
- limit = 0;
- }
- }
- last[limit] = '\0';
- return num;
- }
- // 前后翻转字符串
- char *reverse_str(char *str)
- {
- char *start = str;
- char *left = str;
- char ch;
- if (str != NULL)
- {
- // 定位到字符串的最后一个字符
- while (*str++)
- ;
- str -= 2;
- while (left < str)
- {
- ch = *left;
- *left++ = *str;
- *str-- = ch;
- }
- }
- return start;
- }
- char *append_result(char *result, char ch)
- {
- char *last = result;
- int limit = 0;
- int times = 1;
- // 定位到字符串的末尾
- while (last[limit++] != '\0')
- {
- if (limit >= INCREMENT)
- {
- limit = 0;
- times++;
- last += INCREMENT;
- }
- }
- last[limit - 1] = ch;
- if (limit >= INCREMENT)
- {
- result = (char *)realloc(result, INIT_SIZE + INCREMENT * times);
- last += INCREMENT;
- }
- last[limit] = '\0';
- return result;
- }
- // 将两个字符串对应的数值相加
- char *add_two_strs(char *str1, char *str2)
- {
- int carry = 0; // 存放进位
- int num1, num2, num3;
- char *result;
- result = (char *)malloc(INIT_SIZE);
- if (result == NULL)
- {
- exit(1);
- }
- // 字符串的存放顺序跟加法规则相反
- // 需要先反转字符串
- str1 = reverse_str(str1);
- str2 = reverse_str(str2);
- // 两个字符串按位相加
- while (*str1 != '\0' || *str2 != '\0')
- {
- num1 = *str1 - '0';
- num2 = *str2 - '0';
- if (*str1 == '\0')
- {
- num1 = 0;
- }
- else
- {
- str1++;
- }
- if (*str2 == '\0')
- {
- num2 = 0;
- }
- else
- {
- str2++;
- }
- num3 = num1 + num2 + carry;
- if (num3 > 9)
- {
- append_result(result, num3 - 10 + '0');
- carry = 1;
- }
- else
- {
- append_result(result, num3 + '0');
- carry = 0;
- }
- }
- if (carry)
- {
- append_result(result, carry + '0');
- }
- result = reverse_str(result);
- return result;
- }
- int main(void)
- {
- char *num1;
- char *num2;
- char *result;
- num1 = get_num();
- num2 = get_num();
- result = add_two_strs(num1, num2);
- printf("计算结果是:%s\n", result);
- return 0;
- }
复制代码
感觉好像不对,自己还在找原因
// 将两个字符串对应的数值相加
char *add_two_strs(char *str1, char *str2)
{
int carry = 0; // 存放进位
int num1, num2, num3;
char *result;
result = (char *)malloc(INIT_SIZE);
if (result == NULL)
{
exit(1);
}
memset(result, 0, INIT_SIZE); // 初始化填0。因为字符串是以 \0为以束标志。
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