[#EVP_DigestInit_ex]
= EVP_DigestInit_ex
:mrdocs:

Initialise digest context `ctx` for algorithm `type.`

== Synopsis

Declared in `<openssl/evp.h>`

[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
int
EVP_DigestInit_ex(
    xref:EVP_MD_CTX.adoc[EVP_MD_CTX]* ctx,
    xref:EVP_MD.adoc[EVP_MD] const* type,
    xref:ENGINE.adoc[ENGINE]* impl);
----

== Return Value

1 on success, or 0 on error.

== Parameters

[cols="1,4"]
|===
| Name| Description
| *ctx*
| Digest context to initialise (from EVP_MD_CTX_new()).
| *type*
| Digest algorithm (for example from EVP_sha256()), or NULL to reuse the previous type.
| *impl*
| Legacy ENGINE implementing `type,` or NULL for the default implementation.
|===


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