C++ strlen error in Big C++

Question

I've been working through some of the programs in Big C++ and after I copied append.cpp, Eclipse was telling me 'strlen' was not declared in this scope on line 8. I took a look online, and I thought it was because I had to include the <cstring> library, but that didn't solve it. What's wrong?

append.cpp:

#include <iostream>    

using namespace std;

void append(char s[], int s_maxlength, const char t[])
{
    int i = strlen(s); // error occurs here
    int j = 0;
    while(t[j] != '\0' && i < s_maxlength)
    {
         s[i] = t[j];
         i++;
         j++; 
    }
    //Add zero terminator
    s[i] = '\0';
 }

int main()
{
    const int GREETING_MAXLENGTH = 10;
    char greeting[GREETING_MAXLENGTH + 1] = "Hello";
    char t[] = ", World!";
    append(greeting, GREETING_MAXLENGTH, t);
    cout << greeting << "\n";
    return 0;
 }

Including `` should fix it (and does for me). But why are you messing around with dangerous C-style string manipulation in C++? — Mike Seymour, Aug 15 '13 at 18:27
@H2C03, I'm running this in Eclipse using g++. I tried including the library, but I still received the same error. — Andrew, Aug 15 '13 at 18:29
Also, try to actually compile it. It's maybe just that the static analyzer in Eclipse is being dumb, but the compiler will run just fine (as it should). — , Aug 15 '13 at 18:29
@H2C03, I ran it in a different text editor and compiled it manually. It works now. Seems Eclipse just has a couple of issues... — Andrew, Aug 15 '13 at 18:32
Show us the actual source file that exhibits the problem. The code in your question doesn't have `#include `. Add `#include `, verify that the compiler complains, and copy-and-paste your exact source file, plus the exact error message, into your question. — Keith Thompson, Aug 15 '13 at 18:33
@DanielKamilKozar, my apologies, I was referencing this book: http://www.amazon.com/Big-C-Cay-S-Horstmann/dp/0471470635 — Andrew, Aug 15 '13 at 18:33
@DanielKamilKozar I believe its a book, though never heard of it either — SwiftMango, Aug 15 '13 at 18:33
Just a note - void append(char s[], int s_maxlength, const char t[]) is bad practice - passing arrays using [] syntax is syntactically strange, and invokes some strange corners of the C++ language that many are not familiar with. If you must pass raw arrays around, the correct syntax is char*. If your book uses char name[] as function arguments, I strongly recommend getting a better book. — Stewart, Aug 15 '13 at 18:37
@Stewart, gotcha. I think I'll toss this book aside and go with a different one — Andrew, Aug 15 '13 at 18:42
Have a look at this list for recommendations: http://stackoverflow.com/q/388242/1025391 — moooeeeep, Aug 15 '13 at 18:43
That it compiles for one compiler does not actually prove anything regarding other compilers in the case of missing headers. — user2672165, Aug 15 '13 at 19:26

score 4 · Accepted Answer · answered Aug 15 '13 at 18:35

Including the <cstring> header should solve (should have solved) the issue. My suspicion was correct: it was only Eclipse being dumb, it gave you a false positive.

In cases like this, don't believe the IDE! Always try to compile the source text - if the compiler accepts it, then the static analysis tool in the IDE was wrong.

C++ strlen error in Big C++

1 Answers1