my program

what is wrong with this code. the problem is flagged as /*here*/

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

#define stringsize1 256 /*length of original*/
#define stringsize2 80 /*length of second string*/
#define numsize 10


void insert(char original[], char sub[],int pos); /*function*/

main()
{

char str1[stringsize1], str2[stringsize2],num[numsize];
int position;
int i;


for (i=0;i<5;i++)
{
printf("\nPlease enter a character string:\n");
gets(str1);

printf("\nPlease enter the inserting character string:\n");
gets(str2);

printf("\nPlease enter the inserting position:\n");
gets(num);

/*HERE*/position=pos(num);
insert(str1,str2,position);

printf("\nThe new string is:\n");
printf("%s\n",str1);
}

return EXIT_SUCCESS;
}
/*The inserting function body*/

void insert(char origin[], char sub[],int pos)

{
int i, j; /*i=original string,j=substring*/

int firstlength;

int seclength;

char temp[stringsize1]; /*buffer*/

firstlength=strlen( origin);

seclength=strlen( sub);


/*copy the original str to position in buffer*/

for (i=0;i<pos;++i)
temp[i]=origin[i];

/*insert substr to buffer at desired location*/

for (j=0;j<seclength;j++,i++)
temp[i]=sub[j];

/*remainder of original string copied to buffer*/

/*here*/ for (pos<firstlength;pos++;i++)
temp[i]=origin[pos];


/*end the string*/
temp[i]='\0';


/*complete string copied back to the original location*/

strcpy(origin,temp);
}

pos is undefined. that is why it errors.

Well I think the for loop is wrong

for (pos<firstlength;pos++;i++)
temp[i]=origin[pos];

its suppoed to be, for(variable initailisation, condition, incretement/decretement )

you put a conditional for first

try

for(i = 0; i < firstlenght; i++)
{
pos++
temp[i]=origin[pos];
}

ok bye!

From the Visual C++ 6.0 Help file

The for statement can be divided into three separate parts, as shown in Table 5.3.

Table 5.3 for Loop Elements

Syntax Name When Executed Contents
for-init-statement Before any other element of the for statement or the substatement. Often used to initialize loop indices. It can contain expressions or declarations.
expression1 Before execution of a given iteration of the loop, including the first iteration. An expression that evaluates to an integral type or a class type that has an unambiguous conversion to an integral type.
expression2 At the end of each iteration of the loop; expression1 is tested after expression2 is evaluated. Normally used to increment loop indices.


The for-init-statement is commonly used to declare and initialize loop-index variables. The expression1 is often used to test for loop-termination criteria. The expression2 is commonly used to increment loop indices.

The for statement executes the statement repeatedly until expression1 evaluates to zero. The for-init-statement, expression1, and expression2 fields are all optional.

The following for loop:

for( for-init-statement; expression1; expression2 )
{
// Statements
}

is equivalent to the following while loop:

for-init-statement;
while( expression1 )
{
// Statements
expression2;
}

drop num[numsize] in this line:
char str1[stringsize1], str2[stringsize2],num[numsize];

change this:
gets(num);

to this:
scanf(&position);

or better yet, in my opinion, use streams rather than C style functions for input.

drop this line:
position=pos(num);