A function to return a string representation of an integer
/*
Beginning C, Third Edition
By Ivor Horton
ISBN: 1-59059-253-0
Published: Apr 2004
Publisher: apress
*/
#include <stdio.h>
/* Convert an integer to a string */
/* Caller must allocate string array */
/* Function returns the string to allow */
/* Use of the function in an expression. */
char* itoa(int n, char str[])
{
int i = 0; /* Loop counter */
int negative = 0; /* Indicate negative integer */
int length = 0; /* Length of string */
int temp = 0; /* Temporary storage */
if(negative = (n<0)) /* Is it negative? */
n = -n; /* make it positive */
/* Generate digit characters in reverse order */
do
{
str[i++] = '0'+n%10; /* Create a rightmost digit */
n /= 10; /* Remove the digit */
}while(n>0); /* Go again if there's more digits */
if(negative) /* If it was negative */
str[i++] = '-'; /* Append minus */
str[i] = '\0'; /* Append terminator */
length = i; /* Save the length */
/* Now reverse the string in place */
/* by switching first and last, */
/* second and last but one, etc */
for(i = 0 ; i<length/2 ;i++)
{
temp = str[i];
str[i] = str[length-i-1];
str[length-i-1] = temp;
}
return str; /* Return the string */
}
void main()
{
char str[15]; /* Stores string representation of integer */
long testdata[] = { 30L, -98L, 0L, -1L, 999L, -12345L};
int i = 0; /* Loop control variable */
for (i = 0 ; i< sizeof testdata/sizeof(long) ; i++)
printf("Integer value is %d, string is %s\n", testdata[i], itoa(testdata[i],str));
}
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