How deeply does Modern C, Third Edition cover time_t?

Defines its semantic role and portability limits, but stops short of describing its underlying representation.

Time_t

time_t is an implementation-defined C type used to represent calendar time values.

time_t is a semantic C type for calendar time. Its precision can vary across platforms, so its representation is implementation-dependent rather than a universally fixed numeric format. section 5.2

Comparing calendar times

Obtain timestamps with time(0), then pass two time_t values to difftime(t1, t0) when a time difference suitable for arithmetic is needed. Do not assume that directly subtracting timestamps expresses seconds portably. section 5.2

Table 5.1 Base types according to the four main type classes. Types with a gray background don’t allow for arithmetic; they are promoted before doing arithmetic. Type `char` is special since it can behave like unsigned or signed, depending on the platform. All types in this table are considered to be distinct types, even if they have the same class and precision.

Class		Systematic name	Other name	Rank
Integers	Unsigned	`bool`	`_Bool`	0
		`unsigned char`		1
		`unsigned short`		2
		`unsigned int`	`unsigned`	3
		`unsigned long`		4
		`unsigned long long`		5
	[Un]signed	`char`		1
	Signed	`signed char`		1
		`signed short`	`short`	2
		`signed int`	`signed` or `int`	3
		`signed long`	`long`	4
		`signed long long`	`long long`	5
Floating point	Real	`float`
		`double`
		`long double`
	Complex	`float _Complex`	`float complex`
		`double _Complex`	`double complex`
		`long double _Complex`	`long double complex`

Use the specialized arithmetic-types table to compare time_t with clock_t and other semantic types, including their headers and meanings. section 5.2

How Modern C, Third Edition covers it

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Rust in Action: Systems programming concepts and techniquestime_t is a libc type alias representing elapsed whole seconds since the Unix epoch.

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Related concepts

arithmetic typekind of · An arithmetic type is a C type representing integer, floating-point, or complex numeric values.
mktimeproduced by · mktime is a C standard-library function that converts a local broken-down calendar time to time_t while normalizing its fields.
Unix epochmeasures · The Unix epoch is the reference instant at 00:00:00 UTC on January 1, 1970, from which Unix time is measured.
struct timespecpart of · struct timespec is a C structure type representing a time value with integral seconds and a fractional nanosecond component.
type aliaskind of · A type alias is a declaration that gives an existing type an alternative name without creating a distinct type or representation.

This explainer was generated by Manning's knowledge graph from the text of Modern C, Third Edition. The section links point to the parts of the book it draws on.