//operating system ubuntu,linux,Mac Program will work only if you give command like sum 2 3 or sum 4 (sub 4 3) #include #include #include #include /*Sum function implementation*/ int sum(int number1,int number2){ return number1+number2; } /*sub function implementation*/ int sub(int number1,int number2){ return number1-number2; } /*mul function implementation*/ int mul(int number1,int number2){ return number1*number2; } /*divide function implementation*/ float divide(int number1,int number2){ if(number2==0){ printf(\"We can not divide by 0 \ \"); return 0.0f; } return (float)(number1/number2); } char *substring(char *string, int position, int length) { char *pointer; int c; pointer = malloc(length+1); if (pointer == NULL) { printf(\"Unable to allocate memory.\ \"); exit(1); } for (c = 0 ; c < length ; c++) { *(pointer+c) = *(string+position-1); string++; } *(pointer+c) = \'\\0\'; return pointer; } /*Main Function start*/ int main(int argc, char *argv[]){ /*Variable declarations*/ int number1,number2; char *operator,*str1,*str2; char line[50]; char s[2] = \" \"; int errorFlag=0;// checking if user entered more then one operands while(1){ /*User input*/ printf(\"Please Enter the command \"); gets(line); int len=0; for(int i=0; line[i]!=\'\\0\'; ++i){len++;} if(len==0){ return 1; } /*Spliting into Tokens*/ operator = strtok(line, \" \"); if(strcmp(operator,\"bye\")==0){ break; } /*String to integer --- token1*/ number1=atoi(strtok(NULL, s)); /*Removing ( and ) from String*/ str2=strtok(NULL, s); char *content;int length=0; for(int i=0; str2[i]!=\'\\0\'; ++i){length++;} if(str2[0]==\'(\'){ content=substring(str2,2,length-1); char *opr=content; int n1=atoi(strtok(NULL, s)); int n2=atoi(strtok(NULL, s)); /*If user entered more then two operands then it will return some token otherwise it will return NULL pointer*/ if(strtok(NULL, s)!=NULL){ printf(\"You need to enter operator operand1 operand2 \ \"); errorFlag=1; }else{ if(strcmp(opr,\"sum\")==0){ number2=sum(n1,n2); }else if(strcmp(opr,\"sub\")==0){ number2=sub(n1,n2); }else if(strcmp(opr,\"mul\")==0){ number2=mul(n1,n2); } else if(strcmp(opr,\"div\")==0){ number2=divide(n1,n2); } } }else{ number2=atoi(str2); /*If user entered more then two operands then it will return some token otherwise it will return NULL pointer*/ if(strtok(NULL, s)!=NULL){ printf(\"You need to enter operator operand1 operand2 \ \"); errorFlag=1; } } if(errorFlag!=1){ /*Checking operator by strcmp function*/ if(strcmp(operator,\"sum\")==0){ printf(\"Result %d \ \",sum(number1,number2)); }else if(strcmp(operator,\"sub\")==0){ printf(\"Result %d \ \",sub(number1,number2)); }else if(strcmp(operator,\"mul\")==0){ printf(\"Result %d \ \",mul(number1,number2)); } else if(strcmp(operator,\"div\")==0){ printf(\"Result %.2f \ \",divide(number1,number2)); } } } return 0; } /*******************Output***********************/ gopal@gopal:~/Desktop/chegg$ gcc Calculator.c Calculator.c: In function ‘main’: Calculator.c:67:3: warning: implici.

1. //operating system ubuntu,linux,Mac
Program will work only if you give command like
sum 2 3 or
sum 4 (sub 4 3)
#include
#include
#include
#include
/*Sum function implementation*/
int sum(int number1,int number2){
return number1+number2;
}
/*sub function implementation*/
int sub(int number1,int number2){
return number1-number2;
}
/*mul function implementation*/
int mul(int number1,int number2){
return number1*number2;
}
/*divide function implementation*/
float divide(int number1,int number2){
if(number2==0){
printf("We can not divide by 0 ");
return 0.0f;
}
return (float)(number1/number2);
}
char *substring(char *string, int position, int length)
{
char *pointer;
int c;
pointer = malloc(length+1);

2. if (pointer == NULL)
{
printf("Unable to allocate memory. ");
exit(1);
}
for (c = 0 ; c < length ; c++)
{
*(pointer+c) = *(string+position-1);
string++;
}
*(pointer+c) = '0';
return pointer;
}
/*Main Function start*/
int main(int argc, char *argv[]){
/*Variable declarations*/
int number1,number2;
char *operator,*str1,*str2;
char line[50];
char s[2] = " ";
int errorFlag=0;// checking if user entered more then one operands
while(1){
/*User input*/
printf("Please Enter the command ");
gets(line);
int len=0;
for(int i=0; line[i]!='0'; ++i){len++;}
if(len==0){
return 1;
}

3. /*Spliting into Tokens*/
operator = strtok(line, " ");
if(strcmp(operator,"bye")==0){
break;
}
/*String to integer --- token1*/
number1=atoi(strtok(NULL, s));
/*Removing ( and ) from String*/
str2=strtok(NULL, s);
char *content;int length=0;
for(int i=0; str2[i]!='0'; ++i){length++;}
if(str2[0]=='('){
content=substring(str2,2,length-1);
char *opr=content;
int n1=atoi(strtok(NULL, s));
int n2=atoi(strtok(NULL, s));
/*If user entered more then two operands then it will return some token otherwise it will
return NULL pointer*/
if(strtok(NULL, s)!=NULL){
printf("You need to enter operator operand1 operand2 ");
errorFlag=1;
}else{
if(strcmp(opr,"sum")==0){
number2=sum(n1,n2);
}else if(strcmp(opr,"sub")==0){
number2=sub(n1,n2);
}else if(strcmp(opr,"mul")==0){
number2=mul(n1,n2);
} else if(strcmp(opr,"div")==0){
number2=divide(n1,n2);
}

4. }
}else{
number2=atoi(str2);
/*If user entered more then two operands then it will return some token otherwise it will return
NULL pointer*/
if(strtok(NULL, s)!=NULL){
printf("You need to enter operator operand1 operand2 ");
errorFlag=1;
}
}
if(errorFlag!=1){
/*Checking operator by strcmp function*/
if(strcmp(operator,"sum")==0){
printf("Result %d ",sum(number1,number2));
}else if(strcmp(operator,"sub")==0){
printf("Result %d ",sub(number1,number2));
}else if(strcmp(operator,"mul")==0){
printf("Result %d ",mul(number1,number2));
} else if(strcmp(operator,"div")==0){
printf("Result %.2f ",divide(number1,number2));
}
}
}
return 0;
}
/*******************Output***********************/
gopal@gopal:~/Desktop/chegg$ gcc Calculator.c
Calculator.c: In function ‘main’:
Calculator.c:67:3: warning: implicit declaration of function ‘gets’ [-Wimplicit-function-
declaration]

5. gets(line);
^
/tmp/ccgPlkE8.o: In function `main':
Calculator.c:(.text+0x154): warning: the `gets' function is dangerous and should not be used.
gopal@gopal:~/Desktop/chegg$ ./a.out
Please Enter the command sum 2 3
Result 5
Please Enter the command mul 5 (mul 7 3)
Result 105
Please Enter the command sum 2 3 4
You need to enter operator operand1 operand2
Please Enter the command mul 5 (mul 7 3 2)
You need to enter operator operand1 operand2
Please Enter the command mul 5 (mul 7 3) 2
You need to enter operator operand1 operand2
Please Enter the command bye
Solution
//operating system ubuntu,linux,Mac
Program will work only if you give command like
sum 2 3 or
sum 4 (sub 4 3)
#include
#include
#include
#include
/*Sum function implementation*/
int sum(int number1,int number2){
return number1+number2;
}
/*sub function implementation*/
int sub(int number1,int number2){
return number1-number2;
}
/*mul function implementation*/

6. int mul(int number1,int number2){
return number1*number2;
}
/*divide function implementation*/
float divide(int number1,int number2){
if(number2==0){
printf("We can not divide by 0 ");
return 0.0f;
}
return (float)(number1/number2);
}
char *substring(char *string, int position, int length)
{
char *pointer;
int c;
pointer = malloc(length+1);
if (pointer == NULL)
{
printf("Unable to allocate memory. ");
exit(1);
}
for (c = 0 ; c < length ; c++)
{
*(pointer+c) = *(string+position-1);
string++;
}
*(pointer+c) = '0';
return pointer;
}

7. /*Main Function start*/
int main(int argc, char *argv[]){
/*Variable declarations*/
int number1,number2;
char *operator,*str1,*str2;
char line[50];
char s[2] = " ";
int errorFlag=0;// checking if user entered more then one operands
while(1){
/*User input*/
printf("Please Enter the command ");
gets(line);
int len=0;
for(int i=0; line[i]!='0'; ++i){len++;}
if(len==0){
return 1;
}
/*Spliting into Tokens*/
operator = strtok(line, " ");
if(strcmp(operator,"bye")==0){
break;
}
/*String to integer --- token1*/
number1=atoi(strtok(NULL, s));
/*Removing ( and ) from String*/
str2=strtok(NULL, s);
char *content;int length=0;
for(int i=0; str2[i]!='0'; ++i){length++;}
if(str2[0]=='('){
content=substring(str2,2,length-1);

8. char *opr=content;
int n1=atoi(strtok(NULL, s));
int n2=atoi(strtok(NULL, s));
/*If user entered more then two operands then it will return some token otherwise it will
return NULL pointer*/
if(strtok(NULL, s)!=NULL){
printf("You need to enter operator operand1 operand2 ");
errorFlag=1;
}else{
if(strcmp(opr,"sum")==0){
number2=sum(n1,n2);
}else if(strcmp(opr,"sub")==0){
number2=sub(n1,n2);
}else if(strcmp(opr,"mul")==0){
number2=mul(n1,n2);
} else if(strcmp(opr,"div")==0){
number2=divide(n1,n2);
}
}
}else{
number2=atoi(str2);
/*If user entered more then two operands then it will return some token otherwise it will return
NULL pointer*/
if(strtok(NULL, s)!=NULL){
printf("You need to enter operator operand1 operand2 ");
errorFlag=1;
}
}
if(errorFlag!=1){
/*Checking operator by strcmp function*/
if(strcmp(operator,"sum")==0){
printf("Result %d ",sum(number1,number2));
}else if(strcmp(operator,"sub")==0){

9. printf("Result %d ",sub(number1,number2));
}else if(strcmp(operator,"mul")==0){
printf("Result %d ",mul(number1,number2));
} else if(strcmp(operator,"div")==0){
printf("Result %.2f ",divide(number1,number2));
}
}
}
return 0;
}
/*******************Output***********************/
gopal@gopal:~/Desktop/chegg$ gcc Calculator.c
Calculator.c: In function ‘main’:
Calculator.c:67:3: warning: implicit declaration of function ‘gets’ [-Wimplicit-function-
declaration]
gets(line);
^
/tmp/ccgPlkE8.o: In function `main':
Calculator.c:(.text+0x154): warning: the `gets' function is dangerous and should not be used.
gopal@gopal:~/Desktop/chegg$ ./a.out
Please Enter the command sum 2 3
Result 5
Please Enter the command mul 5 (mul 7 3)
Result 105
Please Enter the command sum 2 3 4
You need to enter operator operand1 operand2
Please Enter the command mul 5 (mul 7 3 2)
You need to enter operator operand1 operand2
Please Enter the command mul 5 (mul 7 3) 2
You need to enter operator operand1 operand2
Please Enter the command bye