Question

Write a C program that calculates and displays the sum of all fourdigit numbers in the line. The only include to use is <stdio.h>. The only keywords:void, int, char, while,if, else, and return. The only library functions:printf(), getchar().The only predefined constant:EOF.

Input            output

3153\n           3153

00020005\n 7

999578585    error

456 5443       error

6574y435      error

Answer 1

`Hey,

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#include <stdio.h>
int main()
{
char ch[1000];
scanf("%s",ch);
int i=0;
while(ch[i]!='\0')
{
if(ch[i]<'0'||ch[i]>'9')
{
printf("error\n");
return 0;
}
i++;
}
if(i%4!=0)
{
printf("error\n");
return 0;
}
int sum=0,ct=i;
for(i=0;i<ct;i=i+4)
{
sum=sum+(ch[i]-'0')*1000+(ch[i+1]-'0')*100+(ch[i+2]-'0')*10+(ch[i+3]-'0');
}
printf("%d\n",sum);
return 0;
}

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