Implement atoi to convert a string to an integer.
Hint: Carefully consider all possible input cases. If you want a challenge, please do not see below and ask yourself what are the possible input cases.
Notes: It is intended for this problem to be specified vaguely (ie, no given input specs). You are responsible to gather all the input requirements up front.
方法
注意溢出她按、符號以及main()里其他的特殊情況
c代碼
#include <assert.h>
#include <limits.h>
int myAtoi(char* str) {
while(*str == ' ')
str++;
int sign = 1;
if(*str == '-') {
sign = -1;
str++;
}
else if(*str == '+')
str++;
int result = 0;
while(*str != '\0') {
if(*str>='0' && *str<='9') {
if((result > INT_MAX/10) || (result==INT_MAX/10 && *str>'7')) {
if(sign == 1)
return INT_MAX;
return INT_MIN;
}
result = result*10 + *str-'0';
}
else
return sign*result;
str++;
}
return sign*result;
}
int main() {
assert(myAtoi("123111111") == 123111111);
assert(myAtoi("a1") == 0);
assert(myAtoi(" 111111111111111111111") == INT_MAX);
assert(myAtoi("-111111111111111111111111111") == INT_MIN);
assert(myAtoi("123aaa") == 123);
assert(myAtoi("-1") == -1);
assert(myAtoi("+-2") == 0);
return 0;
}
