1# log.h 2 3 4## Overview 5 6Defines the logging functions of the HiLog module. 7 8Before outputting logs, you must define the service domain, and log tag, use the function with the specified log type and level, and specify the privacy identifier. 9 10**Log domain**: service domain of logs. You can define the value as required. Its value is a hexadecimal integer ranging from 0x0 to 0xFFFF. If the value exceeds the range, logs cannot be printed. 11 12**Log tag**: a string used to identify the class, file, or service behavior. 13 14**Log level**: DEBUG, INFO, WARN, ERROR, or FATAL. 15 16**Parameter format**: printf format string, which starts with a % character, including a parameter type identifier and a variable parameter. 17 18**Privacy identifier**: **{public}** or **{private}** added between the % character and the parameter type identifier in each parameter. 19 If no privacy identifier is added, the parameter is considered to be **private**. 20 21Example 22 23Define the service domain and tag: 24 25``` 26#define LOG_DOMAIN 0x0201 27#define LOG_TAG "MY_TAG" 28``` 29 30Print the log: 31 32``` 33HILOG_WARN(LOG_APP, "Failed to visit %{private}s, reason:%{public}d.", url, errno); 34``` 35 36Output: 37 38``` 3905-06 15:01:06.870 1051 1051 W 0201/MY_TAG: Failed to visit <private>, reason:503. 40``` 41 42**File to include**: <hilog/log.h> 43 44**System capability**: SystemCapability.HiviewDFX.HiLog 45 46**Since**: 8 47 48**Related module**: [HiLog](_hi_log.md) 49 50 51## Summary 52 53 54### Macros 55 56| Name| Description| 57| -------- | -------- | 58| [LOG_DOMAIN](_hi_log.md#log_domain) 0 | Indicates the service domain for a log file.| 59| [LOG_TAG](_hi_log.md#log_tag) NULL | Indicates the string constant used to identify the class, file, or service. A tag can contain a maximum of 31 bytes. If a tag exceeds this limit, it will be truncated. Chinese characters are not recommended because garbled characters or alignment problems may occur. | 60| [OH_LOG_DEBUG](_hi_log.md#oh_log_debug)(type, ...) ((void) [OH_LOG_Print](_hi_log.md#oh_log_print)((type), [LOG_DEBUG](_hi_log.md), [LOG_DOMAIN](_hi_log.md#log_domain), [LOG_TAG](_hi_log.md#log_tag), __VA_ARGS__)) | Indicates DEBUG logs. This is a function-like macro. Before using this macro, define the log service domain and log tag. Generally, you need to define them at the beginning of the source file.| 61| [OH_LOG_INFO](_hi_log.md#oh_log_info)(type, ...) ((void) [OH_LOG_Print](_hi_log.md#oh_log_print)((type), [LOG_INFO](_hi_log.md), [LOG_DOMAIN](_hi_log.md#log_domain), [LOG_TAG](_hi_log.md#log_tag), __VA_ARGS__)) | Indicates INFO logs. This is a function-like macro. Before using this macro, define the log service domain and log tag. Generally, you need to define them at the beginning of the source file.| 62| [OH_LOG_WARN](_hi_log.md#oh_log_warn)(type, ...) ((void) [OH_LOG_Print](_hi_log.md#oh_log_print)((type), [LOG_WARN](_hi_log.md), [LOG_DOMAIN](_hi_log.md#log_domain), [LOG_TAG](_hi_log.md#log_tag), __VA_ARGS__)) | Indicates WARN logs. This is a function-like macro. Before using this macro, define the log service domain and log tag. Generally, you need to define them at the beginning of the source file. | 63| [OH_LOG_ERROR](_hi_log.md#oh_log_error)(type, ...) ((void) [OH_LOG_Print](_hi_log.md#oh_log_print)((type), [LOG_ERROR](_hi_log.md), [LOG_DOMAIN](_hi_log.md#log_domain), [LOG_TAG](_hi_log.md#log_tag), __VA_ARGS__)) | Indicates ERROR logs. This is a function-like macro. Before using this macro, define the log service domain and log tag. Generally, you need to define them at the beginning of the source file. | 64| [OH_LOG_FATAL](_hi_log.md#oh_log_fatal)(type, ...) ((void) [OH_LOG_Print](_hi_log.md#oh_log_print)((type), [LOG_FATAL](_hi_log.md), [LOG_DOMAIN](_hi_log.md#log_domain), [LOG_TAG](_hi_log.md#log_tag), __VA_ARGS__)) | Indicates FATAL logs. This is a function-like macro. Before using this macro, define the log service domain and log tag. Generally, you need to define them at the beginning of the source file.| 65 66 67### Types 68 69| Name| Description| 70| -------- | -------- | 71| typedef void(\* [LogCallback](_hi_log.md#logcallback)) (const [LogType](_hi_log.md#logtype) type, const [LogLevel](_hi_log.md#loglevel) level, const unsigned int domain, const char \*tag, const char \*msg) | Defines a function for customizing the processing of logs in the callback. | 72 73 74### Enums 75 76| Name| Description| 77| -------- | -------- | 78| [LogType](_hi_log.md#logtype) { LOG_APP = 0 } | Enumerates the log types. | 79| [LogLevel](_hi_log.md#loglevel) {<br>LOG_DEBUG = 3,<br>LOG_INFO = 4,<br>LOG_WARN = 5,<br>LOG_ERROR = 6,<br>LOG_FATAL = 7<br>} | Enumerates the log levels. | 80 81 82### Functions 83 84| Name| Description| 85| -------- | -------- | 86| int [OH_LOG_Print](_hi_log.md#oh_log_print) ([LogType](_hi_log.md#logtype) type, [LogLevel](_hi_log.md#loglevel) level, unsigned int domain, const char \*tag, const char \*fmt,...) __attribute__((__format__(os_log | Outputs logs of the specified **type**, **level**, **domain**, **tag**, and variables determined by the format specifier and privacy identifier in the printf format. | 87| int int [OH_LOG_PrintMsg](_hi_log.md#oh_log_printmsg) ([LogType](_hi_log.md#logtype) type, [LogLevel](_hi_log.md#loglevel) level, unsigned int domain, const char \*tag, const char \*message) | Outputs constant log strings of the specified **type**, **level**, **domain**, and **tag**. | 88| int [OH_LOG_PrintMsgByLen](_hi_log.md#oh_log_printmsgbylen) ([LogType](_hi_log.md#logtype) type, [LogLevel](_hi_log.md#loglevel) level, unsigned int domain, const char \*tag, size_t tagLen, const char \*message, size_t messageLen) | Outputs constant log strings of the specified **domain**, **tag**, and **level**. The tag and string length must be specified. Unlike **OH_LOG_PrintMsg**, this API allows strings without terminators. | 89| int [OH_LOG_VPrint](_hi_log.md#oh_log_vprint) ([LogType](_hi_log.md#logtype) type, [LogLevel](_hi_log.md#loglevel) level, unsigned int domain, const char \*tag, const char \*fmt, va_list ap) __attribute__((__format__(os_log | Outputs logs of specified **type**, **level**, **domain**, **tag**, and variables determined by the format specifier and privacy identifier in the printf format. The variables are of the **va_list** type. | 90| int bool [OH_LOG_IsLoggable](_hi_log.md#oh_log_isloggable) (unsigned int domain, const char \*tag, [LogLevel](_hi_log.md#loglevel) level) | Checks whether logs of the specified service domain, tag, and level can be printed. | 91| void [OH_LOG_SetCallback](_hi_log.md#oh_log_setcallback) ([LogCallback](_hi_log.md#logcallback) callback) | Registers a callback function. | 92| void [OH_LOG_SetMinLogLevel](_hi_log.md#oh_log_setminloglevel) ([LogLevel](_hi_log.md#loglevel) level) | Sets the minimum log level. When a process prints logs, both the minimum log level and global log level are verified.<br>Therefore, the minimum log level cannot be lower than the global log level. The default [global log level](../../dfx/hilog.md#displaying-and-setting-log-levels) is **Info**.| 93