Variable seems to crash program after is has been passed.

[AhabsWhiteWhale]

I cannot figure out how to fix my line 33 error. I believe I have successfully passed the variable "rows" but it then crashes!? Is it because it is defined incorrectly in the prototype?

  //Libraries
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <math.h>

//Function Prototypes
char ReadInRecipientsName(void);
int  OutputToFileORstdOut(void);
//int TreeToFile(void);
int  AskUserForRows(void);
int CreateGreetingCard(int inVal, char a[75]);


//Begin
int main ()
{
	//Local Declarations
	char myString;
	int choice;
	int inVal = 0;
	int choice2;
	
	

	//Function Calls
	myString = ReadInRecipientsName();

	choice = OutputToFileORstdOut();

	//choice2 = TreeToFile();

	AskUserForRows();

	inVal = CreateGreetingCard(inVal, myString);

	//Displaying Stuff

	//Exit Program
	return 0;
}
//******************************************FUNCTIONS**************************************
//Function ReadInRecipientsName
	char ReadInRecipientsName(void)
	{
		//Local Declarations
		char a[75];

		//User Prompt
		printf("Please enter recipient: ");
		scanf("%s", &a);
		strlen("a"); 
	
		//Return
		return a[75];
	}
//Function OutputToFileORstdOut
	int OutputToFileORstdOut(void)
	{
		//Local Declarations
		int b = 0;

		//User Prompt
		printf("Please enter a number greater than zero to output to the stdOut \n or enter a number less than zero to output to a file: ");
		scanf("%d", &b);

		//Return
		return b;
	}
//Function AskUserForRows
	int AskUserForRows(void)
	{
		//Local Declarations
		int localVal = 0;

		//User Prompt
		printf("Please enter the number of rows: ");
		scanf("%d", &localVal);
	
		//Return
		return localVal;
	}
//Function TreeToFile
	int TreeToFile(void)
	{
		//Local Declarations
		FILE* fp1;
		char FileName1;
		//User Prompt
		printf("Please enter a name for your file. \n");
		scanf("%s", &FileName1);
		fp1 = fopen ("Libraries\Documents\FileName1.txt", "w");
		printf("Your Christmas card was placed here at -> C:\\\\%s");
	}
//Function CreateGreetingCard
	int CreateGreetingCard(int inVal, char a[75])
	{
		//Local Declarations
		int i;
		int k;
		int rows;
		int location;
		char myString[75];

		//Work
		//Top of border
		for (i=1;i<=80;++i)
		{
		printf("_");
		}
		printf("\n");

		//Chrsitmas Tree Build
		for (k=1;k<=(rows-1);++k)
		{
			printf("|");
			for (i=1;i<=79;++i)
			{
				if(((39-(k-1))<=i) && (i <= (39+(k-1))))
				{
					printf("*");
				}
				else
				{
						printf(" ");
				}
			}
			printf("|\n");
		}
		for (i=1;i<=81;++i) //tree base
		{
			if ((i==1) || (i==80))
			{
				printf("|");
			}
			if ((i>37)&&(i<41))
			{
				printf("*");
			}
			else
			{
				printf(" ");
			}
		}
		printf("\n");
		if(rows<60)//empty space
		{
		for (k=(rows+1);k<=60;++k)
			{
				for (i=1;i<=81;++i)
					{
					if ((i==1) || (i==81))
					{
						printf("|");
					}
					else
					{
						printf(" ");
					}
					}
				printf("\n");
			}
		}
		
		location = floor((float)(((19+strlen(myString))/2)));
		for(i=1;i<=81;i++) //greeting message centered at bottom of card
		{
			if(i==1 || i==81)
			{
				printf("|");
			}

			if (i==(39-location))
			{
				printf("Happy Holidays:%s!!",myString);
				i=i+(21+strlen(myString));
			}

			else
			{
				printf(" ");
			}
		}
			printf("\n");
			for(i=1;i<=80;++i)
			{
				printf("-");
			}
	}

[yulingo]

AskUserForRows() returns an int, which you never assign to anything. You also have a local variable called inVal in your main which you've initialized to zero, and so you're passing zero to CreateGreetingCard().

inVal = AskUserForRows();

inVal = CreateGreetingCard(inVal, myString);

Edit: You're not passing your string correctly to CreateGreetingCard(). You cannot return an array from a function. You can return a pointer to your array, and then pass it into your function.

Alternatively, you can use C++ strings, cin, cout, and avoid a lot of this mess... unless you have to write this using C headers only.

[ats15]

In CreateGreetingCard rows is undefined. Also inVal is not used