Why strconv?

Real programs constantly convert between strings and numbers: parsing URL query parameters, reading environment variables, formatting IDs, serialising config. The strconv package is the standard library's dedicated module for these conversions — faster and more explicit than fmt.Sprintf / fmt.Sscanf.

int ↔ string

Atoi = ASCII to integer. Itoa = integer to ASCII. These are the most common calls in real Go code.

ParseInt — control base and bit size

strconv.ParseUint and strconv.FormatInt(n, base) mirror this API.

float64 ↔ string

Format verbs: 'f' = decimal, 'e' = scientific, 'g' = shortest of f/e.

bool ↔ string

ParseBool accepts: "1", "t", "T", "TRUE", "true", "True", "0", "f", "F", "FALSE", "false", "False".

Handling *strconv.NumError

When parsing fails, the error is a *strconv.NumError with structured fields:

Quote and Unquote

Useful for generating code, writing config parsers, and producing safe debug output.

strconv vs fmt for performance

strconv.Itoa(n) is measurably faster than fmt.Sprintf("%d", n) because it avoids reflection and interface boxing. In hot paths (log lines, IDs, counters), prefer strconv.