Question 1

How do I get a value by key using jsmn?

Accepted Answer

You must manually traverse the token array: find the object token, then iterate through its children to match key strings and extract corresponding value positions. This requires custom code for each JSON structure.

Question 2

jsmn vs cJSON: which should I use for embedded C?

Accepted Answer

jsmn is lighter with zero dependencies, ideal for extreme resource constraints. cJSON offers easier data access but is larger. Choose jsmn for minimal footprint, cJSON for faster development with more features.

Question 3

Does jsmn validate JSON syntax thoroughly?

Accepted Answer

No, jsmn only performs basic token recognition and may not catch all errors like mismatched brackets or invalid escapes. You need to add validation logic if robustness is required.

Question 4

Can jsmn parse floating-point numbers from JSON?

Accepted Answer

jsmn tokenizes numbers as primitives but doesn't parse them. You must extract the substring and use functions like strtod() to convert to float, adding an extra step.

Question 5

How to handle incremental JSON parsing with jsmn in a stream?

Accepted Answer

Call jsmn_parse() repeatedly with new data chunks and check for JSMN_ERROR_PART; when parsing completes, it returns the token count. This allows efficient streaming without buffering the entire JSON.

Question 6

Is jsmn thread-safe for multi-threaded applications?

Accepted Answer

jsmn uses local parser and token state, so it can be thread-safe if each thread has its own instances. However, there's no built-in locking, so manage synchronization externally.

Jsmn

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