identifier expected, too few arguments to function (C)

user_19000692 0
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My code: I have tried multiple ways to fix this but to no avail. I have to use scanf in the code so I cannot replace it with fgets as many people have told me to. Can someone tell me what's wrong with my code?

#include <stdio.h>

float Parallel(float R1, float R2);

void main(void) {
    char circ;
    float R1, R2, R3;
    
    printf("Select Circuit [A/B/X]: ");
    scanf("%c", &circ);
    
    if (circ == 'A') {
        printf("Enter R1 and R2: ");
        scanf("%f%f", &R1, &R2);
        printf("%f%f", R1, R2);
        Parallel(float R1, float R2);
        printf("Total resistance for Circuit A is %.2f Ohm", RT);
    }
    
    if (circ == 'B') {
        printf("Enter R1, R2 and R3: ");
        scanf("%f%f%f", &R1, &R2, &R3);
        Parallel(float R1, float R2);
        RT = RT + R3;
        printf("Total resistance for Circuit B is %.2f Ohm", RT);
    }

    if (circ == 'X') {
        printf("That's All");
    }
}
        
float Parallel(float R1, float R2);
{
    float RT;
    RT = 1 / (1 / R1 + 1 / R2);
    return RT;
}
c
2 Answers

There is a syntax error in the definition of Parallel: the extra ; should be removed. Putting the { on the same line would have made this mistake obvious:

float Parallel(float R1, float R2) {
    float RT;
    RT = 1 / (1 / R1 + 1 / R2);
    return RT;
}

The calls to the function Parallel are incorrect too: Parallel(float R1, float R2) should be changed to:

    RT = Parallel(R1, R2);

Also note that main must be defined with a return type of int.

Here is a modified version with a loop to perform tasks iteratively:

#include <stdio.h>

float Parallel(float R1, float R2);

int main() {
    char circ;
    float R1, R2, R3;
    
    for (;;) {
        printf("Select Circuit [A/B/X]: ");
        if (scanf(" %c", &circ) != 1)
            return 1;
    
        if (circ == 'A') {
            printf("Enter R1 and R2: ");
            if (scanf("%f%f", &R1, &R2) != 2)
                return 1;
            printf("%f%f", R1, R2);
            RT = Parallel(R1, R2);
            printf("Total resistance for Circuit A is %.2f Ohm\n", RT);
        } else
        if (circ == 'B') {
            printf("Enter R1, R2 and R3: ");
            if (scanf("%f%f%f", &R1, &R2, &R3) != 3)
                return 1;
            RT = Parallel(R1, R2);
            RT = RT + R3;
            printf("Total resistance for Circuit B is %.2f Ohm\n", RT);
        } else
        if (circ == 'X') {
            printf("That's All\n");
            return 0;
        } else {
            printf("Invalid option\n");
        }
    }
}
        
float Parallel(float R1, float R2) {
    float RT;
    RT = 1 / (1 / R1 + 1 / R2);
    return RT;
}
user_45932670

Replace 2 occurrences of Parallel(float R1, float R2); with float RT=Parallel(R1,R2);. As pointed out by others, the code you have is not how to call a function nor do you use the result.

Remove a stray semi-colon in the line float Parallel(float R1, float R2); toward the end of the code. The one at the start is correct in a prototype but not in a function definition.

Amend the line void main(void) to int main(void) and add return 0; to the end of main(). You may not want a return value but this keeps C sweet. ;)

PS: It's a long time since I studied electricity. I can't validate you calculations!

#include <stdio.h>
float Parallel(float R1, float R2);
int main(void)
{
    char circ;
    float R1, R2, R3;
    
    printf("Select Circuit [A/B/X]: ");
    scanf("%c", &circ);
    
    if(circ == 'A')
    {
        printf("Enter R1 and R2: ");
        scanf("%f%f", &R1, &R2);
        printf("%f%f", R1, R2);
        float RT=Parallel(R1,R2);
        printf("Total resistance for Circuit A is %.2f Ohm", RT);
    }
    
    if(circ == 'B')
    {
        printf("Enter R1, R2 and R3: ");
        scanf("%f%f%f", &R1, &R2, &R3);
        float RT=Parallel(R1,R2);
        RT = RT + R3;
        printf("Total resistance for Circuit B is %.2f Ohm", RT);
    }

    if(circ == 'X')
    {
        printf("That's All");
    }
    return 0;
}
    
float Parallel(float R1, float R2)
{
    float RT;
    RT = 1/(1/R1+1/R2);
    return RT;
}
user_42136620
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