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#include <stdio.h>
float conv(float f);
main(){
    float fahr, celsius;
	float lower, upper, step;
	lower = 0;
	upper = 300;
	step = 20;
	fahr = lower;
	while(fahr <= upper){
		celsius = conv(fahr);
		printf("%3.0f\t%6.1f\n", fahr,  celsius);
		fahr = fahr + step;
		return 0;
	}
float conv(float f, float celsius){
	celsius = (5.0 / 9.0) * (fahr - 32.0);
	return celsius;
}
}

prog.c:3:1: warning: return type defaults to ‘int’ [-Wreturn-type]
prog.c: In function ‘main’:
prog.c:20:1: warning: control reaches end of non-void function [-Wreturn-type]
/home/8p7v8l/ccccKlmp.o: In function `main':
prog.c:(.text.startup+0x13): undefined reference to `conv'
collect2: error: ld returned 1 exit status

Standard output is empty