C atoi() function
C atoi() function - Convert a string to an integer
The atoi() function is used to convert a character string to an integer value.
Syntax:
int atoi(const char *str)
Parameters:
Name | Description | Required /Optional |
---|---|---|
str | String to be converted. | Required |
Return value from atoi()
- Returns an integer value that is produced by interpreting the input characters as a number.
- If the function cannot convert the input to a value of that type return value is 0.
- The return value is undefined in the case of an overflow.
Example: atoi() function
The following example shows the usage of atoi() function.
#include <stdlib.h>
#include <stdio.h>
int main(void)
{
int in_val;
char *s;
s = " -4938";
printf("String value: %s",s);
in_val= atoi(s);
printf("\nInteger value = %d\n",in_val);
s = "+4938";
printf("\nString value: %s",s);
in_val= atoi(s);
printf("\nInteger value = %d\n",in_val);
s = "4938";
printf("\nString value: %s",s);
in_val= atoi(s);
printf("\nInteger value = %d\n",in_val);
s = "0038";
printf("\nString value: %s",s);
in_val= atoi(s);
printf("\nInteger value = %d\n",in_val);
s = "003800";
printf("\nString value: %s",s);
in_val= atoi(s);
printf("\nInteger value = %d\n",in_val);
}
Output:
String value: -4938 Integer value = -4938 String value: +4938 Integer value = 4938 String value: 4938 Integer value = 4938 String value: 0038 Integer value = 38 String value: 003800 Integer value = 3800
C Programming Code Editor:
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C Programming: Tips of the Day
What's the point of const pointers?
const is a tool which you should use in pursuit of a very important C++ concept:
Find bugs at compile-time, rather than run-time, by getting the compiler to enforce what you mean.
Even though it does not change the functionality, adding const generates a compiler error when you're doing things you didn't mean to do. Imagine the following typo:
void foo(int* ptr) { ptr = 0;// oops, I meant *ptr = 0 }
If you use int* const, this would generate a compiler error because you're changing the value to ptr. Adding restrictions via syntax is a good thing in general. Just don't take it too far -- the example you gave is a case where most people don't bother using const.
Ref : https://bit.ly/33Cdn3Q
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