Problems with pointers

This is a discussion on Problems with pointers within the C Programming forums, part of the General Programming Boards category; I am trying to write a math engine. So far, I'm still working on the addition portion of the code: ...

  1. #1
    Registered User
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    Jan 2009
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    103

    Problems with pointers

    I am trying to write a math engine. So far, I'm still working on the addition portion of the code:

    Code:
    #include <stdio.h>
    #include <stdlib.h>
    #include <string.h>
    
    void whatOperation(void);
    void add(char[], char[]);
    int main (void) {
    	printf("Welcome to the NumberChopper!\n\n\n\n");
    	whatOperation();
    	return 0;
    }
    
    //find out which function to execute
    void whatOperation(void) {
    		char functionRead[1000];
    		char addFunction[1000]=" add";
    		
    		printf("Please enter the function with parameters: ");
    		scanf("%s", &functionRead);
    		if(strncmp(functionRead, addFunction, 4)==1) {
    			add(functionRead, addFunction);
    		}
    		else {
    			printf("Hey you! Don't fall asleep at the keyboard! \n");
    			printf("%s", addFunction);
    		}
    }
    
    //add function
    int countCharacters(char functionRead) {
    	int charactersInInput=0;
    	while(functionRead[charactersInInput]!="\n") {
    		charactersInInput++;
    	}
    	return charactersInInput++;
    	
    }
    void add (char functionRead[], char addFunction[]) {
    	printf("Add function successfully acessed.\n");
    	
    	//Pointers
    	char *functionReadPtr=functionRead+7;
    	int charactersInInput=0;
    	char *testPointer = functionRead;
    	char integers[1000];
    	
    	printf("Test pointer: %s \n", testPointer);
    	printf("Parameter pointer: %s \n", functionReadPtr );
    	
    	
    	
    	
    	
    	
    }
    When I build it with CodeLite I get:
    Code:
    C:/Documents and Settings/Dhaivat Pandya/Desktop/helloWorld.c/NumberChopper/NumberChopper.c: In function `countCharacters':
    C:/Documents and Settings/Dhaivat Pandya/Desktop/helloWorld.c/NumberChopper/NumberChopper.c:32: error: subscripted value is neither array nor pointer
    mingw32-make.exe[1]: *** [Debug/NumberChopper.o] Error 1
    mingw32-make.exe: *** [All] Error 2
    ----------Build Ended----------
    1 errors, 0 warnings

    I don't understand the problem

  2. #2
    pwns nooblars
    Join Date
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    Location
    Portland, Or
    Posts
    1,094
    Code:
    int countCharacters(char functionRead)
    It seems you are not passing an array or pointer to the function. Instead it is just a char.

  3. #3
    DESTINY BEN10's Avatar
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    Quote Originally Posted by Poincare View Post
    I am trying to write a math engine. So far, I'm still working on the addition portion of the code:

    Code:
    #include <stdio.h>
    #include <stdlib.h>
    #include <string.h>
    
    void whatOperation(void);
    void add(char[], char[]);
    int main (void) {
    	printf("Welcome to the NumberChopper!\n\n\n\n");
    	whatOperation();
    	return 0;
    }
    
    //find out which function to execute
    void whatOperation(void) {
    		char functionRead[1000];
    		char addFunction[1000]=" add";
    		
    		printf("Please enter the function with parameters: ");
    		scanf("%s", &functionRead);
    		if(strncmp(functionRead, addFunction, 4)==1) {
    			add(functionRead, addFunction);
    		}
    		else {
    			printf("Hey you! Don't fall asleep at the keyboard! \n");
    			printf("%s", addFunction);
    		}
    }
    
    //add function
    int countCharacters(char functionRead) {
    	int charactersInInput=0;
    	while(functionRead[charactersInInput]!="\n") {
    		charactersInInput++;
    	}
    	return charactersInInput++;
    	
    }
    void add (char functionRead[], char addFunction[]) {
    	printf("Add function successfully acessed.\n");
    	
    	//Pointers
    	char *functionReadPtr=functionRead+7;
    	int charactersInInput=0;
    	char *testPointer = functionRead;
    	char integers[1000];
    	
    	printf("Test pointer: %s \n", testPointer);
    	printf("Parameter pointer: %s \n", functionReadPtr );
    	
    	
    	
    	
    	
    	
    }
    When I build it with CodeLite I get:
    Code:
    C:/Documents and Settings/Dhaivat Pandya/Desktop/helloWorld.c/NumberChopper/NumberChopper.c: In function `countCharacters':
    C:/Documents and Settings/Dhaivat Pandya/Desktop/helloWorld.c/NumberChopper/NumberChopper.c:32: error: subscripted value is neither array nor pointer
    mingw32-make.exe[1]: *** [Debug/NumberChopper.o] Error 1
    mingw32-make.exe: *** [All] Error 2
    ----------Build Ended----------
    1 errors, 0 warnings

    I don't understand the problem
    i think '&' should be removed from the red portion.coz while inputting a string using scanf '&' is not used. correct me if i'm wrong.
    HOPE YOU UNDERSTAND.......

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  4. #4
    Registered User
    Join Date
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    Location
    Russia
    Posts
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    Code:
        if(strncmp(functionRead, addFunction, 4)==1) {
    use > 0 for check, because it is not guaranteed by the standard, that it will be only 1

    about your problem
    Code:
    int countCharacters(char functionRead) {
    it is an array, it must be char functionRead[] or char *functionRead
    Oh, it was said
    Last edited by c.user; 04-26-2009 at 06:22 AM.

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