x <- rbinom(200,1,0.5)
lambda <- exp(0.5*x)
y <- rexp(200,lambda)
c <- runif(200,0,3)
test <- list(time=pmin(y,c),status=as.numeric(c<y),x=x)

coxph(Surv(time, status) ~ x, test)

index <- 1:200
B <- 200
beta.boot <- numeric(length=B)
for(b in 1:B)
{
	i <- sample(index,length(index),rep=TRUE)
	fit <- coxph(Surv(time[i], status[i]) ~ x[i], test)
	beta.boot[b] <- fit$coef
}
sd(beta.boot,na.rm=TRUE)