Thread: strcmp()

I'm having trouble with strcmp(). I've read a topic on it, but couldn't understand.


I'm using strcmp to compare a variable (that comes from fgets-sscanf pair) with the string "DATA" and others.

I declared the variable as char, and already tried to put a limit on the number of characters of the variable both on strcmp and on the declaration of the variable, but it still doesn't work.
Could you give me some help?

Here is the code segment:

Code:

void leitura(char linha[200], info informacao){


    char verifica;


    /*Usa-se if e [strcmp] para verificar sscanfs*/


    sscanf(linha,"%s",&verifica);


    if(strcmp(verifica[4],"DATA")==0){


        sscanf(linha,"DATA %d %d %d\n",&informacao.dia,&informacao.mes,&informacao.ano);
        informacao.aviso=1;
    
                }


    if(strcmp(verifica[4],"AREA")==0){


        sscanf(linha,"AREA %d %d %d %d\n",&informacao.x1,&informacao.y1,&informacao.x2,&informacao.y2);
        informacao.aviso=2;
                }


    if(strcmp(verifica[9],"INDIVIDUO")==0){


        sscanf(linha,"INDIVIDUO %d %d %d %d\n",&informacao.especie,&informacao.individuo,&informacao.x_individuo,&informacao.y_individuo);
        informacao.aviso=3;
                    }


    if(strcmp(verifica[7],"COLONIA")==0){


        sscanf(linha,"COLONIA %d %d %d %d %d\n",&informacao.especie_col,&informacao.colonia,&informacao.tamanho,&informacao.x_colonia,&informacao.y_colonia);
        informacao.aviso=4;
                    }


    
    }

Code:

 char verifica;

this is a char ,not a string.
Hope this helps

verifica it's a character, not an array of characters.
Try char verifica[200]; and check again arguments of strcmp.

I had already done that and the Warning is passing argument 1 of ‘strcmp’ makes pointer from integer without a cast

Can you post the updated try?

Here it is, this is a function, if you want I can post my main too.

Code:

void leitura(char linha[200], info informacao){


	char verifica[200];


	/*Usa-se if e [strcmp] para verificar sscanfs*/


	sscanf(linha,"%s",&verifica);


	if(strcmp(verifica[4],"DATA")==0){


		sscanf(linha,"DATA %d %d %d\n",&informacao.dia,&informacao.mes,&informacao.ano);
		informacao.aviso=1;
	
				}


	if(strcmp(verifica[4],"AREA")==0){


		sscanf(linha,"AREA %d %d %d %d\n",&informacao.x1,&informacao.y1,&informacao.x2,&informacao.y2);
		informacao.aviso=2;
				}


	if(strcmp(verifica[9],"INDIVIDUO")==0){


		sscanf(linha,"INDIVIDUO %d %d %d %d\n",&informacao.especie,&informacao.individuo,&informacao.x_individuo,&informacao.y_individuo);
		informacao.aviso=3;
					}


	if(strcmp(verifica[7],"COLONIA")==0){


		sscanf(linha,"COLONIA %d %d %d %d %d\n",&informacao.especie_col,&informacao.colonia,&informacao.tamanho,&informacao.x_colonia,&informacao.y_colonia);
		informacao.aviso=4;
					}


	
	}

Thanks for the help!

This compiles??
You have as argument char linha[200]
When i need to pass something like that i use to write

Code:

void leitura(char* linha, int linhaSize, info informacao){..

when i call the function i will pass 200 as 2nd parameter.Then inside the body of the function,you are able to treat linha as an array

then inside what do I do so the function knows 200 is linha's size?

This is for your convenience.If you do not need the size,do not pass it as a parameter

Oh,so I'm not obliged to pass the size of linha into my new function?
Okay,

Thanks a lot, I'll see if it works and I'll update here

Originally Posted by std10093

This compiles??
You have as argument char linha[200]
When i need to pass something like that i use to write

Code:

void leitura(char* linha, int linhaSize, info informacao){..

when i call the function i will pass 200 as 2nd parameter.Then inside the body of the function,you are able to treat linha as an array

Yeah, it compiles. Arrays decay to a pointer to the first element when passed to a function, so the compile ignores any number in the left-most set of array brackets. If there's only one set of brackets, it ignores the number in there. It's not wrong to put it, but it's pointless. The following are all equivalent:

Code:

void leitura(char linha[200])  // the 200 is ignored, which is like having empty brackets, and...
void leitura(char linha[])     // the empty brackets decay to a pointer
void leitura(char *linha)    // so it ends up equivalent to this

Note, this is only true for the left-most set of brackets. If you have a multi-dimensional array, you must specify all the dimensions except the left-most.

Originally Posted by Chinchila

then inside what do I do so the function knows 200 is linha's size?

You pass a second parameter, like linhaSize, as std10093 suggested. Wherever you call the function, you must pass the correct size of the array into that parameter.

Well, now strcmp is saying I'm making a pointer from an integer:

Code:

void leitura(char *linha, info informacao){


	char verifica;


	/*Usa-se if e [strcmp] para verificar sscanfs*/


	sscanf(linha,"%s",&verifica);


	if(strcmp(verifica,"DATA")==0){


		sscanf(linha,"DATA %d %d %d\n",&informacao.dia,&informacao.mes,&informacao.ano);
		informacao.aviso=1;
	
				}


	if(strcmp(verifica,"AREA")==0){


		sscanf(linha,"AREA %d %d %d %d\n",&informacao.x1,&informacao.y1,&informacao.x2,&informacao.y2);
		informacao.aviso=2;
				}


	if(strcmp(verifica,"INDIVIDUO")==0){


		sscanf(linha,"INDIVIDUO %d %d %d %d\n",&informacao.especie,&informacao.individuo,&informacao.x_individuo,&informacao.y_individuo);
		informacao.aviso=3;
					}


	if(strcmp(verifica,"COLONIA")==0){


		sscanf(linha,"COLONIA %d %d %d %d %d\n",&informacao.especie_col,&informacao.colonia,&informacao.tamanho,&informacao.x_colonia,&informacao.y_colonia);
		informacao.aviso=4;
					}


	
	}

So, what should I do to make it right?
The logic is, I take from fgets(linha) into verifica with a sscanf, and then I want it to be compared in strcmp.
I'm in the dark. Thanks