Go by Example: String to Int
Parsing strings into integers requires handling potential errors. Go provides `Atoi` for simple cases and `ParseInt` for more control.
Code
package main
import (
"fmt"
"strconv"
)
func main() {
// 1. strconv.Atoi (Simple)
// "Atoi" stands for ASCII to Integer.
// Converts to 'int'. Returns value and error.
s1 := "123"
i1, err := strconv.Atoi(s1)
if err != nil {
panic(err)
}
fmt.Printf("Atoi: %d (type %T)\n", i1, i1)
// 2. strconv.ParseInt (Advanced)
// ParseInt(str, base, bitSize)
// base: 0 (auto-detect), 10, 16, etc.
// bitSize: 0 (int), 8, 16, 32, 64.
s2 := "100"
i2, err := strconv.ParseInt(s2, 10, 64)
if err != nil {
panic(err)
}
fmt.Printf("ParseInt: %d (type %T)\n", i2, i2)
// 3. Handling Errors
_, err = strconv.Atoi("invalid")
if err != nil {
fmt.Println("Error:", err)
}
}
Explanation
Converting strings to integers involves parsing text that may not always be valid, so Go's functions for this task always return an error alongside the result. The most common function is strconv.Atoi (ASCII to Integer), which attempts to parse a string as a base-10 int. It is a convenient wrapper around the more general ParseInt function.
For scenarios requiring specific integer sizes (like int64) or different bases (like hexadecimal), strconv.ParseInt is used. It takes a base (0 to 64) and a bit size (0 to 64) as arguments. A base of 0 allows the function to infer the base from string prefixes like "0x" for hex. Always check the returned error to ensure the string was a valid number.
- strconv.Atoi: Simple conversion to
int. - strconv.ParseInt: Control over base and bit size (returns
int64). - Error Handling: Always check for invalid syntax or range errors.