atoi 字串轉換為數字
阿新 • • 發佈：2019-01-31
#include <iostream>
#include <typeinfo>
#include <cmath>
#include <cctype>
using namespace std;
int myAtoi(char *str)
{
if(str == NULL)
return -1;
int n = 0;
int isNegative = 0;
int num = 0;
char *p = str;
char *start = NULL;
while(*p)
{
if(isdigit(*p) && n == 0)
{
start = p;
}
if(isdigit(*p))
{
n++;
}
p++;
}
p = str;
if(*p == '-')
{
isNegative = 1;
}
for(int i = 0; i < n; ++i)
{
char tmp = *start++;
if(tmp != '0'|| num != 0)
{
tmp -= '0';
num += tmp * (int) pow(10.0,n-1-i);
}
}
if(isNegative)
{
num = -num;
}
return num;
}
int main()
{
cout<<"num = "<<myAtoi("-bb001231a");
}
#include <typeinfo>
#include <cmath>
#include <cctype>
using namespace std;
int myAtoi(char *str)
{
if(str == NULL)
return -1;
int n = 0;
int isNegative = 0;
int num = 0;
char *p = str;
char *start = NULL;
while(*p)
{
if(isdigit(*p) && n == 0)
{
start = p;
}
if(isdigit(*p))
{
n++;
}
p++;
}
p = str;
if(*p == '-')
{
isNegative = 1;
}
for(int i = 0; i < n; ++i)
{
char tmp = *start++;
if(tmp != '0'|| num != 0)
{
tmp -= '0';
num += tmp * (int) pow(10.0,n-1-i);
}
}
if(isNegative)
{
num = -num;
}
return num;
}
int main()
{
cout<<"num = "<<myAtoi("-bb001231a");
}