C string.Not getting the desired output. How can I input such number

Question

What is wrong with the given C code? Why I am unable to get the desired output?
When I Input "123 + hello = 234" I expect the output as "123 hello 234".
But the Output is "123 + hello"?
Please someone explain the logic with whats wrong and the correct way to get the input.
Also please suggest references for further reading of similar topic.

#include<stdio.h>
int main()
{
    char str1[11],str2[11],str3[11],ch1,ch2;    
    scanf("%s",str1);
    scanf("%c",&ch1);
    scanf("%s",str2);
    scanf("%c",&ch2);
    scanf("%s",str3);    
    printf("%s %s %s\n",str1,str2,str3);

    return 0;
}

Answer 1

as per your input

123 + hello = 234

The whitespace matters. The immediate whitespace after 123 goes to ch1 and + to str2.

Without having an explicit whitespace in %c, it will consider the whitespace in input as valid input for scan.

Try something like

scanf(" %c",&ch1);
       ^
       |

Which tells scanf() to discard all leading whitespace characters and read the next first non-whitespace character, in your case +.

^{Sidenote: Always check the success ogf scanf() by checking the return value. Good Practice}