How to use string as parameter VCS

VEX V5 Technical Support UNOFFICIAL Tech Support
1

how can i utilize strings as a parameter in functions? Using vex coding studio… Currently getting and error message with this code:

error message: 5:05:36 – warning – warning: result of comparison against a string literal is unspecified (use strncmp instead) -Wstring-compare]
} else if (dir == “left”){
^ ~~~~~~
./main.cpp:70:20:


void turn(char dir, double target) {
    
    if (dir == "right"){
        
       // turn right to target 
                      
    } else if (dir == "left"){
        
       // turn left to target

    }
    
       task::sleep(50);    
}
2

Id use an


std::string

, it has alot more features and it’s easier to work with

3

or an enumeration for what you’re trying to do with it

4

Interestingly enough, the compiler is telling you how to fix it by using strcmp() function:

    if ( strcmp( dir, "right" ) ==0 ) {
    }

dir should be declared as:
*char *dir
*

**Man page for strcmp()
**

STRCMP(3)                BSD Library Functions Manual                STRCMP(3)

NAME
     strcmp, strncmp -- compare strings

LIBRARY
     Standard C Library (libc, -lc)

SYNOPSIS
     #include <string.h>

     int
     strcmp(const char *s1, const char *s2);

     int
     strncmp(const char *s1, const char *s2, size_t n);

DESCRIPTION
     The strcmp() and strncmp() functions lexicographically compare the null-
     terminated strings s1 and s2.

     The strncmp() function compares not more than n characters.  Because
     strncmp() is designed for comparing strings rather than binary data,
     characters that appear after a `\0' character are not compared.

RETURN VALUES
     The strcmp() and strncmp() functions return an integer greater than,
     equal to, or less than 0, according as the string s1 is greater than,
     equal to, or less than the string s2.  The comparison is done using
     unsigned characters, so that `\200' is greater than `\0'.

SEE ALSO
     bcmp(3), memcmp(3), strcasecmp(3), strcoll(3), strxfrm(3), wcscmp(3)

STANDARDS
     The strcmp() and strncmp() functions conform to ISO/IEC 9899:1990
     (``ISO C90'').

BSD                            October 11, 2001                            BSD