Version: 3.x

# Index inspection functions

These functions provide metadata about an H3 index, such as its resolution or base cell, and provide utilities for converting into and out of the 64-bit representation of an H3 index.

## h3GetResolution​

int h3GetResolution(H3Index h);

Returns the resolution of the index.

## h3GetBaseCell​

int h3GetBaseCell(H3Index h);

Returns the base cell number of the index.

## stringToH3​

H3Index stringToH3(const char *str);

Converts the string representation to H3Index (uint64_t) representation.

Returns 0 on error.

## h3ToString​

void h3ToString(H3Index h, char *str, size_t sz);

Converts the H3Index representation of the index to the string representation. str must be at least of length 17.

## h3IsValid​

int h3IsValid(H3Index h);

Returns non-zero if this is a valid H3 index.

## h3IsResClassIII​

int h3IsResClassIII(H3Index h);

Returns non-zero if this index has a resolution with Class III orientation.

## h3IsPentagon​

int h3IsPentagon(H3Index h);

Returns non-zero if this index represents a pentagonal cell.

## h3GetFaces​

void h3GetFaces(H3Index h, int* out);

Find all icosahedron faces intersected by a given H3 index and places them in the array out. out must be at least of length maxFaceCount(h).

Faces are represented as integers from 0-19, inclusive. The array is sparse, and empty (no intersection) array values are represented by -1.

## maxFaceCount​

int maxFaceCount(H3Index h3);

Returns the maximum number of icosahedron faces the given H3 index may intersect.