Why does the code snippet fail when assigning a large integer literal to a `long` variable, but works when using `long long`?

Understanding the Behavior of 'long long' in C/C

When working with integer data types in C/C , it's crucial to understand the nuances of integer representations. One specific data type, 'long long,' often raises questions about its behavior.

Consider the following code snippet:

#include <stdio.h>

int main() {
    int num1 = 1000000000;
    long num2 = 1000000000;
    long long num3;
    // num3 = 100000000000;
    long long num4 = ~0;

    printf("%u %u %u", sizeof(num1), sizeof(num2), sizeof(num3));
    printf("%d %ld %lld %llu", num1, num2, num3, num4);

    return 0;
}</stdio.h>

When executing this code, you may encounter an error if you uncomment the commented line:

// num3 = 100000000000;

The error reads:

"error: integer constant is too large for long type"

However, when you compile and run the code without uncommenting that line, it outputs values significantly larger than 10000000000. Why?

Understanding Integer Literals and Data Types

In C/C , integer literals are constants that represent numeric values. The type of an integer literal is determined by a suffix, such as 'L' or 'LL'. Without a suffix, the literal is treated as an 'int' by default.

In the provided code, the value '100000000000' is too large to be represented in a 'long' data type. Therefore, you must add a suffix to indicate the intended data type.

Assigning the Literal Correctly

To resolve the error, you should assign the literal using the correct suffix, as shown below:

long long num3 = 100000000000LL;

The suffix 'LL' signifies that the literal should be treated as a 'long long' type, which can accommodate a larger range of values.

The updated line assigns the value '100000000000' to 'num3' without triggering an error. This ensures that the variable 'num3' can hold and operate on the intended large numeric value.

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