实现字符串数字乘法运算
如输入11, 2 输出 22; 输入 -10, 2,输出-20
//实现字符串数字乘法运算
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
void
reverseStr(char* str)
{
int ii = 0;
int len = strlen(str);
char temp;
for (ii = 0; ii < len/2; ii++)
{
temp = str[len-1-ii];
str[len-1-ii] = str[ii];
str[ii] = temp;
}
return;
}
void
delFirststzero(char* str)
{
int is_neg = 0;
int len = strlen(str);
char* p_str = str + len - 1;
int ii = len - 1;
reverseStr(str);
if (*p_str == '-')
{
*p_str = 0;
is_neg = 1;
p_str--;
ii--;
}
for (; ii > 0; ii--)
{
if (*p_str != '0')
{
if (is_neg)
{
*(p_str+1) = '-';
}
break;
}
*p_str = 0;
p_str--;
}
reverseStr(str);
return;
}
void
mul(const char* num1, const char* num2, char* resault)
{
const char* p_num1 = NULL;
const char* p_num2 = NULL;
const char* p_temp = NULL;
char* p_res = resault;
char temp;
int len1 = 0;
int len2 = 0;
int ii = 0;
int jj = 0;
int res_neg = 0;
if (!num1 || !num2 || !resault)
{
return;
}
len1 = strlen(num1);
len2 = strlen(num2);
p_num1 = num1 + len1 - 1;
p_num2 = num2 + len2 - 1;
if (num1[0] == '-')
{
len1--;
}
if (num2[0] == '-')
{
len2--;
}
if ((num1[0] != '-' && num2[0] != '-') || (num1[0] == '-' && num2[0] == '-'))
{
res_neg = 0;
}
else
{
res_neg = 1;
}
*p_res = '0';
p_temp = p_num2;
for (ii = 0; ii < len1; ii++, p_num1--)
{
p_res = resault + ii;
p_num2 = p_temp;
for (jj = 0; jj < len2; jj++, p_num2--)
{
temp = *p_res - '0';
temp += (*p_num1 - '0') * (*p_num2 - '0');
*p_res++ = temp % 10 + '0';
*p_res = (*p_res) ? *p_res + temp / 10 : temp / 10 + '0';
}
}
if (res_neg)
{
if (*p_res > '0')
{
p_res++;
}
*p_res = '-';
}
reverseStr(resault);
delFirststzero(resault);
return;
}
int main(int argc, const char* argv[])
{
char rlt[256] = {0};
if (argc < 2)
{
return -1;
}
mul(argv[1], argv[2], rlt);
printf("%s\n", rlt);
return 0;
}