Strings C++

[luan]

Hello. I have a problem with strings in C++.
I'm using gcc/g++ gnu/linux compiler.
How i can do tests with strings and constants in C++?

Eg:
char string[10];
if (string == "test") {
printf("OK");
}

I'm wating for help.
Thanks.

 

[MHL]

Hello. I have a problem with strings in C++.
I'm using gcc/g++ gnu/linux compiler.
How i can do tests with strings and constants in C++?

Eg:
char string[10];
if (string == "test") {
printf("OK");
}

I'm wating for help.
Thanks.

you either use strcmp or create a == operator. you can't compare string
to string directly.

hope this will help.

 

[luan]

Hello. I have a problem with strings in C++.
I'm using gcc/g++ gnu/linux compiler.
How i can do tests with strings and constants in C++?

Eg:
char string[10];
if (string == "test") {
printf("OK");
}

I'm wating for help.
Thanks.

you either use strcmp or create a == operator. you can't compare string
to string directly.

hope this will help.

I've used strcmp, but for example if i compare "love" and "ovel" it
will return true.
And its is a problem, cause it isn't true.
Thanks.

 

[Ian Collins]

Hello. I have a problem with strings in C++.
I'm using gcc/g++ gnu/linux compiler.
How i can do tests with strings and constants in C++?

Eg:
char string[10];

That isn't a C++ string.

if (string == "test") {
printf("OK");
}

Use C++ strings.

std::string whatever;

if( whatever == "test ) ...

 

[Simias]

I've used strcmp, but for example if i compare "love" and "ovel" it
will return true.

No, it won't: 'l' != 'o', so it will return `false', that is != 0
(strcmp returns 0 only if both strings are equal, maybe that's your mistake?)

 

[Markus Moll]

Hi

I've used strcmp, but for example if i compare "love" and "ovel" it
will return true.
And its is a problem, cause it isn't true.

$ man strcmp
[...]
The strcmp() function compares the two strings s1 and s2. It returns
an integer less than, equal to, or greater than zero if s1 is found,
respectively, to be less than, to match, or be greater than s2.

You should first know how things work before you try to use them.

Markus

 

[David Harmon]

On 5 Nov 2006 16:11:22 -0800 in comp.lang.c++,

Hello. I have a problem with strings in C++.

Use the std::string class found in #include <string>
See any decent C++ textbook for details.
Avoid using naked char arrays as a string-substitute.

 

[Jim Langston]

Hello. I have a problem with strings in C++.
I'm using gcc/g++ gnu/linux compiler.
How i can do tests with strings and constants in C++?

Eg:
char string[10];
if (string == "test") {
printf("OK");
}

I'm wating for help.
Thanks.

If you use a c++ std::string it'll do what you want.

std::string MyString = "test";
if ( MyString == "test" ) {
std::cout << "OK" << std::endl;
}

If you use C style strings (char array) you gotta use c-string functions.

char MyString[10];
strcpy( MyString, "test" );
if ( strcmp( MyString, "test" ) == 0 ) {
std::cout << "OK" << std:;endl;
}

std::string is much prefered.

 

[arnuld]

Hello. I have a problem with strings in C++.
I'm using gcc/g++ gnu/linux compiler.
How i can do tests with strings and constants in C++?

Eg:
char string[10];
if (string == "test") {
printf("OK");
}

as other folks have mentioned, you are using C in C++. it is not a
standard C++ programme. try this one using C++ strings:

// C++ strings

#include <iostream>
#include <string>

int main() {
std::string s;
std::cout << "guess the word: ";
std::cin >> s;

if(s == "test")
std::cout << "You guessed \n";
else
std::cout << "NOPE, you are wrong.\n";
}

you can customise it to your requirements. i just gave you an idea.

I'm wating for help.

hey, a newbie helped you ;-)

Thanks.

not a problem ;-)


-- arnuld
http://arnuld.blogspot.com

 

[Ron Natalie]

Hello. I have a problem with strings in C++.
I'm using gcc/g++ gnu/linux compiler.
How i can do tests with strings and constants in C++?

Eg:
char string[10];
if (string == "test") {
printf("OK");
}

I'm wating for help.
Thanks.

you either use strcmp or create a == operator. you can't compare string
to string directly.

hope this will help.

You can not create a == operator for arrays or pointers, only
user defined types (classes and enums). The true answer is that
the C++ string class is called string.

 

[Ron Natalie]

I've used strcmp, but for example if i compare "love" and "ovel" it
will return true.
And its is a problem, cause it isn't true.
Thanks.

strcmp doesn't return a boolean. It returns zero if
the strings are equal, or a positive or negative value
if they are not.

 

[Ron Natalie]

No, it won't: 'l' != 'o', so it will return `false', that is != 0
(strcmp returns 0 only if both strings are equal, maybe that's your mistake?)

strcmp returns zero if the strings are equal. The return value is int
not bool.

 

[luan]

Here is my code:
#include <stdio.h>
#include <string.h>
#include <ctype.h>

#define false 0;
#define true 1;

typedef int BOOL;

//interpret comand
BOOL Comando(char *cmd) {
int i = 0;
char interp[8];

while ((cmd != ' ') && (cmd != '\0')) {
interp = toupper(cmd);
i++;
}

interp = '\0';

if ((strcmp(interp,"JOGO") == 0)) {
return true;
}
else {
return false;
}

}

int main() {
char comand[50];
printf("OK.\n\r");
fgets(comand,50,stdin);
if (Comando(comand)) {
printf("It's a valid comand.\n\r");
}
else {
printf("It ins't a valid comand.\n\r");
}
return 0;
}

What's wrong?
Thanks.

 

[pzehnder]

Hello. I have a problem with strings in C++.
I'm using gcc/g++ gnu/linux compiler.
How i can do tests with strings and constants in C++?

Eg:
char string[10];
if (string == "test") {
printf("OK");
}

I'm wating for help.
Thanks.

You could try:

char s[10];
....
if (std::string(s) == "test") {
std::cout << "OK" << std::endl;
}

 

[luan]

Hello. I have a problem with strings in C++.
I'm using gcc/g++ gnu/linux compiler.
How i can do tests with strings and constants in C++?

Eg:
char string[10];
if (string == "test") {
printf("OK");
}

I'm wating for help.
Thanks.

You could try:

char s[10];
...
if (std::string(s) == "test") {
std::cout << "OK" << std::endl;
}

when i put:
std::string -> this generate a error =(

 

[Roland Pibinger]

char string[10];
if (string == "test") {
printf("OK");
}

as other folks have mentioned, you are using C in C++. it is not a
standard C++ programme.

What's not standard C++ in the above code? It doesn't print "OK" but
that's another question ...

Best wishes,
Roland Pibinger

 

[Andre Kostur]

Here is my code:
#include <stdio.h>
#include <string.h>
#include <ctype.h>

#define false 0;
#define true 1;

typedef int BOOL;

Why are you redefining the bool type? C++ has one. Use it.

//interpret comand
BOOL Comando(char *cmd) {
int i = 0;
char interp[8];

while ((cmd != ' ') && (cmd != '\0')) {
interp = toupper(cmd);
i++;
}

interp = '\0';

if ((strcmp(interp,"JOGO") == 0)) {
return true;
}
else {
return false;
}

}

int main() {
char comand[50];
printf("OK.\n\r");
fgets(comand,50,stdin);
if (Comando(comand)) {
printf("It's a valid comand.\n\r");
}
else {
printf("It ins't a valid comand.\n\r");
}
return 0;
}

What's wrong?

Doesn't fgets also capture the newline character? Try displaying the
length of the input string in the Commando function. Also, if I entered
a 50 character command in main, you'll get Undefined Behaviour in the
Commando function. Your while loop won't stop at the end of the 8
character array that you've defined in Commando.

 

[Andre Kostur]

Hello. I have a problem with strings in C++.
I'm using gcc/g++ gnu/linux compiler.
How i can do tests with strings and constants in C++?

Eg:
char string[10];
if (string == "test") {
printf("OK");
}

I'm wating for help.
Thanks.

You could try:

char s[10];
...
if (std::string(s) == "test") {
std::cout << "OK" << std::endl;
}

when i put:
std::string -> this generate a error =(

We're not mind-readers. What's the error?

 

[Earl Purple]

Here is my code:
#include <stdio.h>
#include <string.h>
#include <ctype.h>

#define false 0;
#define true 1;

typedef int BOOL;

//interpret comand
BOOL Comando(char *cmd) {
int i = 0;
char interp[8];

while ((cmd != ' ') && (cmd != '\0')) {
interp = toupper(cmd);
i++;
}

interp = '\0';

if ((strcmp(interp,"JOGO") == 0)) {
return true;
}
else {
return false;
}

}int main() {
char comand[50];
printf("OK.\n\r");
fgets(comand,50,stdin);
if (Comando(comand)) {
printf("It's a valid comand.\n\r");
}
else {
printf("It ins't a valid comand.\n\r");
}
return 0;

}What's wrong?

You're in the wrong newsgroup. Try comp.lang.c

 

[Earl Purple]

What is worse is that he has redefined two C++ reserved words with
pre-processors.