将数字字符串转换成整数

问题

将数字字符串转换成整数

算法分析

算法步骤如下：

算法实现

#include <stdio.h>
int atoi(char s[ ]);
main()
{
    char s[20];
    scanf("%s", s);
    printf("%d\n", atoi(s));
}
int atoi(char s[ ])
{
  int i, n, sign;
  for(i=0; s[i] = = ' ' || s[i] = = '\n' || s[i] = = '\t'; i++)
    ;  /* skip white space */
  sign = 1;
  if(s[i] = = '+' || s[i] = = '-')
    sign = (s[i++] = = '+')?1:-1;
  for(n=0; s[i] >= '0' && s[i] <= '9'; i++)
    n = 10*n + s[i] – '0';
  return ( sign * n);
}