ds-algo-study
Version:
Just experimenting with publishing a package
62 lines (44 loc) • 1.84 kB
JavaScript
/* Convert a string to an integer in C, JavaScript, and Ruby
Some Theory - A> The number system ranges from 48 to 59 in chartCodeAt() method
console.log("0".charCodeAt("0")); // 48
console.log("9".charCodeAt("0")); // 57
B> JavaScript's highest integer value that a number can go to without losing precision? - he max safe integer is 231-1, or 2147483647.
*/
// SOLUTION WITHOUT USING REGEXP AND PARSEINT
myAtoi = str => {
let i = 0, numSign = '+', number = '', finalOutputNum = 0, base10Multiplier = 1;
str = str.trim() // remove all whitespaces from both ends
// First move i forward and update sign to take up '-' if '-' is found
// And if a '+' is found just treat it, as if there was nothing before the number and check-out the next number to start building the number with the next loop
if (str[0] === '+') {
i++
} else if (str[0] === '-') {
numSign = '-'
i++
}
// For the above code, I could just use Regexp, like my other solution in my other file.
// Now traverse through the given string argument and build the number string.
for (i ; i < str.length; i++) {
if (str[i].charCodeAt(0) >= 48 && str[i].charCodeAt(0) <= 57) {
number += str[i]
} else {
if (number === "") {
return 0
} else {
break;
}
}
}
// From the above I have a string "number". Now without using parseInt() I will convert it to an integer
for (i = (number.length - 1); i >=0; i--) {
finalOutputNum += base10Multiplier * number[i];
base10Multiplier *= 10;
if ( finalOutputNum > 2147483647 && numSign === '+' ) {
return 2147483647
} else if (finalOutputNum > 2147483648 && numSign === '-' ) {
return -2147483648;
}
}
return ( numSign === '-' ? (-1 * finalOutputNum) : finalOutputNum )
}
console.log(myAtoi("+1")); // => 1