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Defines C++ wrapper to log/print text messages. More...

Classes

Type Name
class eosio::iostream

Variables

Type Name
static iostream cout

Functions

Detailed Description

This API uses C++ variadic templates and type detection to make it easy to print any native type. You can even overload the method for your own custom types. Example:

print( "hello world, this is a number: ", 5 );

Variables Documentation

variable cout (2/2)

iostream eosio::cout;

Functions Documentation

function printhex

void eosio::printhex(
    const void * ptr,
    uint32_t size
)

Prints a block of bytes in hexadecimal

Parameters:

  • ptr - pointer to bytes of interest
  • size - number of bytes to print

function printl

void eosio::printl(
    const char * ptr,
    size_t len
)

Prints string to a given length

Parameters:

  • ptr - a string
  • len - number of chars to print

function print

void eosio::print(
    const char * ptr
)

Prints string

Parameters:

  • ptr - a null terminated string

function print

void eosio::print(
    float num
)

Prints single-precision floating point number (i.e. float)

Parameters:

  • num to be printed

function print

void eosio::print(
    double num
)

Prints double-precision floating point number (i.e. double)

Parameters:

  • num to be printed

function print

void eosio::print(
    long double num
)

Prints quadruple-precision floating point number (i.e. long double)

Parameters:

  • num to be printed

function print

template<typename T, std::enable_if_t<!std::is_integral< std::decay_t< T >>::value, int >>
void eosio::print(
    T && t
)

Prints class object

Parameters:

  • t to be printed

Precondition:

T must implements print() function

function print_f

void eosio::print_f(
    const char * s
)

Prints null terminated string

Parameters:

  • s null terminated string to be printed

function print

template<typename T, std::enable_if_t< std::is_integral< std::decay_t< T >>::value &&std::is_signed< std::decay_t< T >>::value, int >>
void eosio::print(
    T num
)

Prints 8-128 bit signed integer

Parameters:

  • num to be printed

Prints 8-128 bit unsigned integer

Parameters:

  • num to be printed

function print

template<size_t Size>
void eosio::print(
    const fixed_bytes< Size > & val
)

Prints fixed_bytes as a hexidecimal string.

Prints fixed_bytes as a hexidecimal string

Parameters:

  • val to be printed

function print

template<size_t Size>
void eosio::print(
    fixed_bytes< Size > & val
)

Prints fixed_bytes as a hexidecimal string.

Prints fixed_bytes as a hexidecimal string

Parameters:

  • val to be printed

function print

void eosio::print(
    name name
)

Prints a 64 bit names as base32 encoded string

Parameters:

  • name 64 bit name to be printed

function print

void eosio::print(
    eosio::symbol_code sym_code
)

Prints a symbol_code

Parameters:

  • sym_code symbol code to be printed

function print_f

template<typename Arg, typename... Args>
void eosio::print_f(
    const char * s,
    Arg val,
    Args... rest
)

Prints formatted string. It behaves similar to C printf/

Template parameters:

  • Arg - Type of the value used to replace the format specifier
  • Args - Type of the value used to replace the format specifier

Parameters:

  • s - Null terminated string with to be printed (it can contains format specifier)
  • val - The value used to replace the format specifier
  • rest - The values used to replace the format specifier

Example:

print_f("Number of apples: %", 10);

function print

template<typename Arg, typename... Args>
void eosio::print(
    Arg && a,
    Args &&... args
)

Print out value / list of values

Template parameters:

  • Arg - Type of the value used to replace the format specifier
  • Args - Type of the value used to replace the format specifier

Parameters:

  • a - The value to be printed
  • args - The other values to be printed

Example:

const char *s = "Hello World!";
uint64_t unsigned_64_bit_int = 1e+18;
uint128_t unsigned_128_bit_int (87654323456);
uint64_t string_as_unsigned_64_bit = "abcde"_n;
print(s , unsigned_64_bit_int, unsigned_128_bit_int, string_as_unsigned_64_bit);
// Ouput: Hello World!100000000000000000087654323456abcde

function operator<<

template<typename T>
iostream& eosio::operator<<(
    iostream & out,
    const T & v
)

Overload c++ iostream

Template parameters:

  • Arg - Type of the value used to replace the format specifier
  • Args - Type of the value used to replace the format specifier

Parameters:

  • out - Output strem
  • v - The value to be printed

Returns:

iostream& - Reference to the input output stream

Example:

const char *s = "Hello World!";
uint64_t unsigned_64_bit_int = 1e+18;
uint128_t unsigned_128_bit_int (87654323456);
uint64_t string_as_unsigned_64_bit = "abcde"_n;
std::out << s << " " << unsigned_64_bit_int << " "  << unsigned_128_bit_int << " " << string_as_unsigned_64_bit;
// Output: Hello World! 1000000000000000000 87654323456 abcde