Updated 2 years ago

# 8. -string-to-integer-atoi

Use the "Run" button to execute the code.

`!pip install jovian --upgrade --quiet`

`import jovian`

Implement the myAtoi(string s) function, which converts a string to a 32-bit signed integer (similar to C/C++'s atoi function).

The algorithm for myAtoi(string s) is as follows:

- Read in and ignore any leading whitespace.
- Check if the next character (if not already at the end of the string) is '-' or '+'. Read this character in if it is either. This determines if the final result is negative or positive respectively. Assume the result is positive if neither is present.
- Read in next the characters until the next non-digit character or the end of the input is reached. The rest of the string is ignored.
- Convert these digits into an integer (i.e. "123" -> 123, "0032" -> 32). If no digits were read, then the integer is 0. Change the sign as necessary (from step 2).
- If the integer is out of the 32-bit signed integer range [-2^31, 2^31 - 1], then clamp the integer so that it remains in the range. Specifically, integers less than -2^31 should be clamped to -2^31, and integers greater than 2^31 - 1 should be clamped to 2^31 - 1.
- Return the integer as the final result.

Note:

Only the space character ' ' is considered a whitespace character. Do not ignore any characters other than the leading whitespace or the rest of the string after the digits.

```
def myAtoi(s):
if s == "":
return 0
res = ""
sign = 1
n = len(s)
digits = ['0', '1', '2', '3', '4', '5', '6', '7', '8', '9']
#whitespace
for i in range(n):
if s[i] == ' ':
res = s[i + 1:]
if s[0] != ' ':
res = s
print(res, len(res))
#leadsign
if res[0] == '-':
res = res[1:]
sign = -1
elif res[0] == '+':
res = res[1:]
print(res, sign, len(res))
#digits
for j in range(len(res)):
print(j)
if res[j] not in digits and j == 0:
return 0
if res[j] not in digits:
r_int = int(res[:j]) * sign
break
else:
r_int = int(res[:j + 1]) * sign
#bounds
if r_int < -2**31:
r_int = -2**31
if r_int > 2**31 - 1:
r_int = 2**31 - 1
return r_int
# having a lot of trouble with all the testcases just doing the brute force
```