Question

How do I concatenate Strings with C/C++?

I tried the following ways:

PS: errorInfo is a char * I should return it.

        errorInfo = strcat("Workflow: ", strcat(
            workflowToString(workflow).utf8(), strcat(" ERROR: ",
                    errorCode.utf8)));

        sprintf(errorInfo, "Workflow %s ERROR: %s",
            workflowToString(workflow).utf8(), errorCode.utf8());

        errorInfo = "Workflow: " + workflowToString(workflow).utf8() + " ERROR: " + errorCode.utf8;

Just the sprintf compiles but when running my application crash.

PS: I’m using NDK from Android

Answer 1

According to this page strcat does the following:

Appends a copy of the source string to the destination string. The terminating null character in destination is overwritten by the first character of source, and a new null-character is appended at the end of the new string formed by the concatenation of both in destination.

In your implementation, however, "Workflow: " is a constant string. You cannot modify that string, which is what strcat would do. In order to do that, create a string like:

char message[1000];
strcpy(message, "Workflow: ");
strcat(message, "other string");
....

However, be careful about the utf8 character encoding because one utf8 code point could be multiple chars long.