My .c programme gives an object a 'name' when its created. I need to be able to excute different tasks depending on that name. I very new to this and have tried a couple of ways with no success. Here is what I had come up with..
if (name == "james"){
//Do a bunch of stuff
}
if (name == "tom"){
//Do a bunch of stuff
}
This was not successful. Is there a way so that if the 'name' is one thing it wont execute the others?
Thankyou so much for any help
if 'name' is a C++ string, what you have written should work fine. If it's a char[] or char *, use strcmp.
name isn't a C++ string, it should be.Have a look at the library function strcmp. When you use == you will just compare the pointers itself, not the actual string array lying behind them.
name is a string, as he claims.
char* or char[] "strings" in C, because "pointer to char" or "char array" just haven't the same feel.std::string, and '\0' terminated char* or char[] will be usually be called "C-style strings" if the context isn't totally unambiguous.name were an actual std:string, his code were correct).In C, a string is defined as a sequence of characters which are terminated with \0. A string constant is normally represented within `", for example, char a[10] = "hello".
In order to compare two strings, you can use library functions like strcmp() which is available in string.h. Do man strcmp to read more about this function.
#include <stdio.h>
#include <string.h>
int main()
{
char name[] = "tom";
if (strcmp(name, "tom") == 0) {
printf("name is tom! \n");
} else if (strcmp(name, "bob") == 0) {
printf("name is bob! \n");
} else {
printf("who is this?! \n");
}
return 0;
}
The strcmp could have been implemented in the following ways (array and pointer versions for your reference)
int strcmp1(char a[], char b[])
{
int i=0;
while (a[i] == b[i]) {
if (a[i] == '\0')
return 0;
i++;
}
return a[i]-b[i];
}
int strcmp2(char *a, char *b)
{
while (*a == *b) {
if (*a == '\0')
return 0;
a++; b++;
}
return *a-*b;
}
You need to use strcmp as:
if (!strcmp(name,"james")){
Using == compares the contents of name(starting address of the string) with the starting address of the string literal "james" which is certainly now what you want.
strcmp doesn't work with C++ strings. His problem is that he's not declared name with the correct type; if name is std::string, his code should work.
.c file, so he is talking about C not C++.Assuming this is a standard .c program, and that your 'name' is a actually a char* then you're going to have to use the strings.h standard c library for the the strcmp() function.
The equality operator == is for std::string and other string classes.
e.g.
if (strcmp(name,"james")==0){
/* Do stuff */
}
Also, you might consider the switch conditional for multiple tests.
switch requires integral constants. He doesn't have any of these.
int JAMES=1 etc.) might be better given the seemingly fixed flow of control.