Enumerate the Header Fields of an Email

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Demonstrates the read-only Chilkat Email.NumHeaderFields property together with GetHeaderFieldName and GetHeaderFieldValue to enumerate every header field. Indexing is zero-based, so fields run from 0 to NumHeaderFields - 1. Repeated header fields (a field name that appears more than once) are counted separately. This example builds a small email and prints each header field.

Background: A header field is a single Name: value line at the top of a MIME message. The same field name can legitimately appear multiple times — for example, a message can carry several Received lines, one added by each mail server it passed through. That is why enumerating by index (rather than looking up by name) matters: it lets you see every occurrence in the order it appears.

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#include <C_CkEmail.h>

void ChilkatSample(void)
    {
    HCkEmail email;
    int n;
    int i;

    //  Demonstrates the read-only Email.NumHeaderFields property and enumerating each
    //  header field by zero-based index using GetHeaderFieldName and GetHeaderFieldValue.

    email = CkEmail_Create();
    CkEmail_putSubject(email,"Header field enumeration");
    CkEmail_putFrom(email,"mary@example.com");
    CkEmail_AddTo(email,"Joe","joe@example.com");

    n = CkEmail_getNumHeaderFields(email);
    printf("NumHeaderFields = %d\n",n);

    for (i = 0; i <= n - 1; i++) {
        printf("%s: %s\n",CkEmail_getHeaderFieldName(email,i),CkEmail_getHeaderFieldValue(email,i));
    }



    CkEmail_Dispose(email);

    }