warning:overflow in implicit constant conversion


We usually, see this warning in C and C++ when data type overflow happen

In C we have basic data types such as int, float, and char but each data type will have a different range

For example, the range for char is from  -128 to +127

  Suppose, if you assign a char variable with 130[exceeded the normal range of char-128 to +127] then, in that case, it will take a cyclic value[which is 44] and that is known as overflow

#include <iostream>
using namespace std;
int main()
    char a=300;//warning:overflow in implicit constant conversion 
    cout << (int)a<< endl;//Type_casting char a to int a
    return 0;



But, Why you got this warning?

Because you have exceeded the normal range of a data type

But, how to avoid this warning

in short, by being in the range of the data type and not exceeding the normal data type range which you have declared

At the same time, always keep in mind that a char variables are just a single character enclosed within single quotes

Such as

 letters ‘a’,’b’

in addition, you can also assign char to numerical values without a single quote but should be in the range of -128 to 127

Does this warning have any effect on the output of the program?

of course, yes!

Of course, it will alter the accuracy of the result

But, how?

Let’s see an example

for instance, suppose, you have a variable of type char

So, what is the maximum value you can store in char  

in general, the answer is +127

in reality, can we store +128 in char?


But, why?

Because the compiler will throw a warning indicating that you exceeded the normal range of char

until now, okay,

Here’s another one

at this time, suppose you have a variable of char type and you store the value +130 in it

that is, Char x=+130;

At this instant, print the variable x

At this point, you get a result as -126 which is wrong

It should be  +130 but because of this over this overflow the result gets altered and corrupted

to sum up, here are some standard data types range that you should not exceed to avoid warning

standard data types range

Data typerange
char-128 to 127
unsigned char0 to 255
signed char-128 to 127
int-32768 to 32767
unsigned int0 to 65535
signed int-32768 to 32767
short int-32768 to 32767
unsigned short int0 to 65535
signed short int-32768 to 32767
long int-2147483648 to 2147483647
unsigned long int0 to 4294967295
signed long int-2147483648 to 2147483647
float3.4E-38 to 3.4E+38
double1.7E-308 to 1.7E+308
long double3.4E-4932 to 1.1E+4932

Sizes of data types may vary from one compiler to another

16-bit(turbo C/C++)224
32-bit(Visual studio, gcc)244

A 2-byte integer can take values from -32768 to +32767

A 4-byte integer can take values from -2147483648 to +2147483647

Mohammed Anees

Hey there, welcome to aneescraftsmanship I am Mohammed Anees an independent developer/blogger. I like to share and discuss the craft with others plus the things which I have learned because I believe that through discussion and sharing a new world opens up

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