PASS Week 4/14 Solutions

Problem 1


#include <stdio.h>
#include <string.h>
#include <ctype.h>

int main(int argc,char* argv[])
{
    for(int i = argc - 1; i >=0; i--) {
        printf("%s \n", argv[i]);
    }

return 0;
}//end main






Problem 2


#include <stdio.h>
#include <stdlib.h>
#include <string.h>

int main(void)
{
   FILE* fp = NULL;
   char filename[50];
   printf("Enter your file: ");
   fscanf(stdin, "%s", filename);
   fp = fopen(filename, "r");

   if (fp != NULL){
       printf("File exists");
   }
   else{
        printf("Sorry B");
   }
    fclose(fp);

return 0;
}//end main








COMPETITION PROGRAM Un-Mystified


#include <stdio.h>
#include <string.h>
#include <stdbool.h>

void FlushInput(void);
bool FileExists(char*);
bool CreateFile(char*, char*);

int main(void){
    FILE* fIn = NULL;
    char textIn[300];
    char fileName[80];
    char saveFile = 'y';
    bool result = false;

    printf("Enter in some text to save:");

    if(fgets(textIn,300,stdin)){
        printf("Your entered in %d characters.\n", (int) strlen(textIn));
        printf("Enter in the name of a text file: ");
        fscanf(stdin,"%s",fileName);

            if(FileExists(fileName) == true){
                printf("The file exists, enter 'y' to overwrite:");
                FlushInput();
                scanf("%c", &saveFile);

                if(saveFile == 'y')
                    result = CreateFile(textIn, fileName);
                else
                    printf("You chose not to save the data.\n");
            }
            else{
                result = CreateFile(textIn, fileName);
            }//end if-else
    }
    else {
        printf("You did not enter in anything to save.\n");
    }

    if(result)
        printf("You successfully created a file named %s\n", fileName);
    else
        printf("You did not create a file named %s\n", fileName);

    return 0;
}//end main


bool FileExists(char* fileName){
    FILE* fIn = fopen(fileName,"r");

    if(fIn == NULL)
	 	return false;
    else{
        fclose(fIn);
        return true;
    }
}//end function


void FlushInput(void){
    while(getchar() != '\n');
    return;
}//end function


bool CreateFile(char* textIn, char* fName){
    FILE* fPtr = fopen(fName,"w");

    if(fPtr == NULL){
        printf("Error opening file.\n");
        return false;
    }

    else{
        fputs(textIn, fPtr);
        fclose(fPtr);
        return true;
    }//end if-else

}//end function








Problem 3

#include <stdio.h>
#include <stdlib.h>

int main () {
    int i, n;
    int *a = NULL;

    printf("Number of elements to be entered:");
    scanf("%d",&n);

    a = (int*)calloc(n, sizeof(int));

    printf("Enter %d numbers:\n",n);
    for( i=0 ; i < n ; i++ ) {
        scanf("%d",&a[i]);
    }

    printf("The numbers entered are: ");
    for( i=0 ; i < n ; i++ ) {
        printf("%d ",a[i]);
    }

    free( a );

    return(0);
}









Problem 4

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

int main () {
    char *str;

    /* Initial memory allocation */
    str = (char *) malloc(13);
    strcpy(str, "Maryhadalamb");
    printf("String = %s, Address = %u\n", str, str);

    /* Reallocating memory */
    str = (char *) realloc(str, 25);
    strcat(str, ", it stunk!");
    printf("String = %s, Address = %u\n", str, str);

    free(str);

    return(0);
}